USE OF Li2[B12H12] SALT TO ABSORB WATER INTO POLYMERS

ABSTRACT

Methods of adjusting the properties of a composition are provided. The compositions comprise a polymer-containing matrix and a filler comprising a hygroscopic salt. Preferred such salts comprise a cage compound selected from the group consisting of borane cage compounds, carborane cage compounds, metal complexes thereof, residues thereof, mixtures thereof, and/or agglomerations thereof, where the cage compound is not covalently bound to the matrix polymer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority benefit of U.S. Provisional Patent Application Ser. No. 61/374,814, entitled USE OF Li₂[B₁₂H₁₂] SALT TO ABSORB WATER INTO POLYMERS, filed Aug. 18, 2010, the entire disclosure of which are incorporated herein by reference.

GOVERNMENT INTERESTS

The present invention was developed with support from the U.S. government under a contract with the United States Department of Energy, Contract No. DE-NA-0000622. Accordingly, the U.S. government has certain rights in the present invention.

BACKGROUND

1. Technical Field

The present invention is concerned with methods of adjusting or fine-tuning the properties of compositions comprising a polymer(s) with a hygroscopic salt dispersed within the polymer.

2. Description of Related Art

Polymer nanocomposites have been the subject of intense research in recent years. Through the successful incorporation of nanofillers and other nanostructures, polymer nanocomposites have demonstrated advanced material properties including reinforcement, thermal, flame, moisture, and chemical resistance, charge dissipation, barrier/gas transport properties, electrical conductivity and resistance, among others. The high surface area of nanofillers, and thereby their enhanced polymer interfaces, likely contributes to the observed novel and advanced properties. However, the mechanistic details by which reinforcement and other extraordinary properties occur, as well as the exact nature of the interactions between the nanofiller and their polymer matrix are not well understood. In fact, the properties observed in nanocomposites have been divergent, ranging broadly from being reinforcing to plasticizing. In some cases, the glass transition temperatures of polymer nanocomposites increase, decrease, remain unaffected, or additional/new glass transitions are formed, compared to the unmodified host polymer. Thus, given the unpredictable nature of nanocomposite technology, improvements are still desired.

SUMMARY

In one embodiment, the invention provides a method of adjusting the properties of a material. The method comprises providing a composition that comprises: a matrix comprising a polymer; and a filler comprising a hygroscopic salt. The composition is exposed to moisture under conditions for the composition to absorb the moisture.

In another embodiment, the method of adjusting the properties of a material comprises:

providing a composition comprising:

-   -   a matrix comprising a polymer, where the polymer comprises one         or more residues of a cage compound monomer selected from the         group consisting of a borane cage compound monomer, a carborane         cage compound monomer, and mixtures thereof; and     -   a filler comprising a hygroscopic salt; and

exposing the composition to moisture under conditions for the composition to absorb the moisture.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

Embodiments of the present invention are described herein with reference to the attached drawing figures, wherein:

FIG. 1 presents plots of temperature versus tan δ for nanocomposite samples comprising an uncured EVA-OH polymer matrix and various amounts of n-hexyl carborane;

FIG. 2 presents plots of temperature versus tan δ for nanocomposite samples comprising an uncured EVA polymer matrix and various amounts of n-hexyl carborane;

FIG. 3 presents plots of temperature versus tan δ for nanocomposite samples comprising a cured EVA-OH polymer matrix and various amounts of n-hexyl carborane;

FIG. 4 presents plots of temperature versus tan δ for nanocomposite samples comprising an uncured EVA-OH polymer matrix and various amounts of tethered carborane;

FIG. 5 presents plots of temperature versus tan δ for nanocomposite samples comprising an uncured EVA-OH polymer matrix and various amounts of carborane diol;

FIG. 6 presents plots of temperature versus storage modulus for nanocomposite samples comprising an uncured EVA-OH polymer matrix and various amounts of lithium dodecaborate (a.k.a., dilithium dodecahydrododecaborate; Li₂ ²⁺[B₁₂H₁₂]²⁻);

FIG. 7 presents plots of temperature versus loss modulus for nanocomposite samples comprising an uncured EVA-OH polymer matrix and various amounts of lithium dodecaborate;

FIG. 8 presents plots of temperature versus tan δ for nanocomposite samples comprising an uncured EVA-OH polymer matrix and various amounts of lithium dodecarborate;

FIG. 9 presents plots of melt viscosity as a function of borane cage compound content for nanocomposite samples comprising an uncured EVA-OH polymer matrix and various amounts of lithium dodecaborate, carborane diol, tethered carborane, or n-hexyl carborane;

FIG. 10 presents plots of tan δ peak maximum as a function of borane cage compound content for nanocomposite samples comprising an uncured EVA-OH polymer matrix and various amounts of lithium dodecaborate, carborane diol, tethered carborane, or n-hexyl carborane;

FIG. 11 presents plots of loss modulus peak maximum as a function of borane cage compound content for nanocomposite samples comprising an uncured EVA-OH polymer matrix and various amounts of lithium dodecaborate, carborane diol, tethered carborane, or n-hexyl carborane;

FIG. 12 presents bar charts comparing Shore A Hardness values for nanocomposite samples having increasing amounts of n-hexyl carborane in EN8 polyurethane matrix;

FIG. 13 a is a scanning electron micrograph of heterogeneous crystalline carborane diol in EN8 polyurethane, where the carborane diol is in the form of agglomerated small crystals;

FIG. 13 b is a scanning electron micrograph of heterogeneous crystalline carborane diol in EN8 polyurethane, where the carborane diol is in the form of a single large crystal;

FIG. 14 presents bar charts comparing change in glass transition temperature (“Tg”) for nanocomposite samples having various borane or carborane fillers and various polymer matrices.

FIG. 15 is a graph showing the rate of change of the respective glass transition temperatures of several samples according to the invention as a function of exposure to atmospheric moisture;

FIG. 16 is a graph depicting the respective storage moduli of several samples according to the invention as a function temperature;

FIG. 17 is a plot of the tan δ of several samples according to the invention as a function temperature;

FIG. 18 is a graph of the storage modulus as a function of temperature of several samples according to the invention, showing the effect can be reversed with drying at elevated temperatures; and

FIG. 19 is a plot of the tan δ of several samples according to the invention as a function temperature, showing that the effect can be reversed with drying at elevated temperatures.

DETAILED DESCRIPTION

The following detailed description of the invention describes specific embodiments in which the invention can be practiced. The embodiments are intended to describe aspects of the invention in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments can be utilized and changes can be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense. The scope of the present invention is defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled.

Various embodiments of the invention concern compositions (e.g., nanocomposites or polymers) containing borane and/or carborane cage compounds or residues thereof. In one or more embodiments, there is provided a nanocomposite comprising a matrix and a filler, where the filler comprises a cage compound selected from the group consisting of a borane cage compound, a carborane cage compound, a metal complex thereof, a residue thereof, mixtures thereof, and agglomerations thereof. As used herein, the term “nanocomposite” shall denote a composition comprising at least two components, where each component contains at least one different molecular species or residue than the other component(s), where such components are not covalently bound to one another, and where at least one of the components has at least one dimension sized less than 100 nm. Matrices suitable for use in nanocomposites in various embodiments of the present invention can comprise a polymer.

As noted above, the various fillers employed in the present invention can contain borane and/or carborane compounds, or residues thereof. As used herein, the term “borane” shall denote a chemical compound consisting of boron and hydrogen atoms, exclusive of any pendant group atoms. Additionally, in various embodiments described herein, the term “boron cage compound” is employed. The terms “boron cage compound” and “borane cage compound” shall be construed as having the same meaning, and each are intended to denote a cage compound (defined below) that is a borane. As used herein, the term “carborane” shall denote a chemical compound consisting of boron, hydrogen, and carbon atoms, exclusive of any pendant group atoms.

As noted above, the borane and/or carborane compounds can be in the form of a cage compound. As used herein, the term “cage compound” is intended to denote a molecule having a polyhedral or substantially polyhedral structure of nido- (a polyhedron missing only one vertex) or above (i.e., polyhedrons missing no vertices; e.g., closo-, hypercloso-, capped-, bicapped-, etc.). Examples of polyhedral shapes suitable for use in the cage compounds of the present invention include, but are not limited to, trigonal bipyramid, octahedron, pentagonal bipyramid, dodecahedron, tricapped trigonal prism, bicapped square antiprism, octadecahedron, and icosahedron. Additionally, cage compounds suitable for use can have one or more of such polyhedral shapes fused together (i.e., a conjuncto-configuration). In various embodiments, the cage compound employed can have a closo-polyhedral structure. Additionally, the cage compound employed can have an icosahedral or pentagonal bipyramidal structure. Furthermore, in various embodiments, the cage compound employed has an icosahedral structure. In addition, cage compounds suitable for use can comprise two or more of such structures tethered together by a linking group such as, for example, the propyl linkage in a carborane 1,3-o-carboranylpropane (i.e. tethered carborane). In one or more embodiments, the cage compound or combination of cage compounds can constitute at least 50, at least 60, at least 70, at least 80, at least 90, or at least 99 weight percent of the above-mentioned filler. In other various embodiments, cage compounds can constitute all or substantially all of the above-mentioned filler.

Cage compounds suitable for use in various embodiments of the present invention can have at least 7, at least 8, at least 9, at least 10, at least 11, or at least 12 cage atoms. As used herein, the term “cage atom” is intended to denote an atom located at and defining a vertex of the polyhedral or substantially polyhedral structure. This is in contrast to atoms that are pendant to the cage compound. Additionally, the cage compounds suitable for use in various embodiments of the present invention can have in the range of from 7 to 20 cage atoms, in the range of from 9 to 15 cage atoms, or in the range of from 11 to 13 cage atoms. In one or more embodiments, the cage compound can have 12 cage atoms. When the cage compound employed is a “tethered” compound, such compound can have a greater number of cage atoms. For instance, when the cage compound employed comprises two cage compound structures tethered together, such compound can have in the range of from 14 to 40 cage atoms, in the range of from 18 to 30 cage atoms, or in the range of from 22 to 26 cage atoms. In one or more embodiments, a “tethered” cage compound can have 24 cage atoms.

As noted above, the cage compounds employed in various embodiments of the present invention can include borane and/or carborane cage compounds. Thus, in one or more embodiments, the cage compound can comprise boron atoms or a combination of boron and carbon atoms as cage atoms. When a carborane cage compound is employed, in various embodiments at least about 50 percent, at least about 60 percent, at least about 70 percent, at least about 80 percent, or at least 90 percent of the cage atoms in the carborane cage compounds are boron atoms. In other embodiments, when a carborane cage compound is employed, carbon atoms can constitute in the range of from 1 to 6, in the range of from 1 to 4, or in the range of from 1 to 2 cage atoms per molecule of the carborane cage compound. When the cage compound employed is a “tethered” carborane, such compound can have in the range of from 2 to 12 carbon cage atoms, in the range of from 2 to 8 carbon cage atoms, or in the range of from 2 to 4 carbon cage atoms.

In various embodiments, the cage compounds suitable for use can comprise one or more pendant atoms or pendant groups. As used herein, the term “pendant” shall be construed as meaning covalently bound to the cage compound. In various embodiments, pendant atoms or pendant groups can be covalently bound to one or more cage atoms. Examples of atoms suitable for use as pendant atoms include, but are not limited to, single valence atoms, such as chlorine, bromine, or iodine. Pendant groups (a.k.a., functional groups) suitable for use in various embodiments can generally be either reactive (e.g., carboxyl groups) or generally non-reactive (e.g., unsubstituted, saturated alkyl groups). Examples of pendant groups suitable for inclusion on the cage compounds in various embodiments of the present invention include, but are not limited to, alkyls (e.g., methyl, ethyl, etc.), alkenyls (e.g., vinyl, allyl, etc.), alkynyls, aryls, alkaryls, aralkyls, alkoxys, epoxys, phenyls, benzyls, hydroxys, carboxyls, acyls, carbonyls, aldehydes, carbonate esters, carboxylates, ethers, esters, hydroperoxides, peroxides, carboxamides, amines, imines, imides, azides, azos, cyanates, isocyanates, nitrates, nitriles, nitrites, nitros, nitrosos, pyridyls, phosphinos, phosphates, phosphonos, sulfos, sulfonyls, sulfonyls, sulfhydryls, thiocyanates, disulfides, silyls, and alkoxy silyls (e.g., triethoxysilyl). As used herein, the term “alkyl” shall denote a univalent group formed by removing a hydrogen atom from a hydrocarbon, and may include heteroatoms. As used herein, the term “aryl” shall denote a univalent group formed by removing a hydrogen atom from a ring carbon in an arene (i.e., a mono- or polycyclic aromatic hydrocarbon), and may include heteroatoms. As used herein, the term “heteroatom” shall denote any atom other than carbon and hydrogen. Examples of heteroatoms suitable for use include, but are not limited to, nitrogen, oxygen, sulfur, phosphorus, chlorine, bromine, or iodine. In various embodiments, cage compounds of the present invention can comprise two or more of such pendant groups. In one or more embodiments, the cage compound can comprise one or more pendant groups selected from the group consisting of a C₁ to C₂₀ n-alkyl, a C₁ to C₁₂ n-alkyl, a C₁ to C₈ n-alkyl, a hydroxy, a carboxy, an epoxy, an isocyanate, a cyanurate, a primary amine, a silyl, an alkoxy silyl, and mixtures of two or more thereof.

In one or more embodiments, metal complexes of cage compounds can be used in various embodiments of the present invention. For instance, cage compounds described herein as suitable for use could constitute one or more ligands in a metal complex. Metals suitable for use in metal-complexed cage compounds include any metal capable of forming an air and moisture stable metal complex. Such metals include, but are not limited to, any Group 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 metal.

In one or more embodiments of the present invention, the cage compound employed can be a stable compound. As used herein, the term “stable,” when referring to cage compounds, shall denote a general lack of decomposition or tendency towards the formation of new covalent bonds with a host matrix during synthesis/formation, storage, and application of the nanocomposites in which the cage compounds are incorporated, with the caveat that all such polymer based materials, including the nanocomposites described herein, are not expected to have an infinite use life and will age to varying degrees based on the severity of the synthesis, storage, and/or application conditions employed and the duration to which the nanocomposites are subjected to such conditions.

In one or more embodiments of the present invention, the cage compound employed can comprise a closo-carborane having the general formula C₂B_(n)H_(n+2), where n can be in the range of from 5 to 10. Additionally, in various embodiments, the cage compound employed can comprise a closo-carborane having the general formula C₂B_(n)H_(n+2), where n is 10 (i.e., closo-dicarbadodecaborane). When the cage compound employed herein is a closo-dicarbadodecaborane, it can be in the ortho- (i.e., 1,2-closo-dicarbadodecaborane), meta- (i.e. 1,7-closo-dicarbadodecaborane), or para- (i.e., 1,12-closo-dicarbadodecaborane) configuration. In one embodiment, the cage compound employed can be a 1,2-closo-dicarbadodecaborane. Additionally, such closo-carboranes can include any one or more of the pendant groups described above. For example, in various embodiments of the present invention, the cage compound employed can comprise a closo-carborane having the general formula R_(x)[C₂B_(n)H_(n+2−x)], where n can be in the range of from 5 to 10, x can be in the range of from 1 to 2, and where each R can be the same or different, and can independently comprise any of the pendant groups mentioned above. For instance, R can be chosen from aliphatic compounds (e.g., n-hexyl) and/or heteroatom-containing aliphatic compounds.

In one or more embodiments of the present invention, the cage compound employed can comprise a closo-carborane salt having the general formula [CB_(n)H_(n+1)]X, where n can be in the range of from 6 to 11, and X can be any of a variety of cationic species. Cationic species suitable for use as X include, but are not limited to, Li⁺, Na⁺, K⁺, Cs⁺, and NR₄ ⁺ (where R is hydrogen or an aliphatic group, for example). Additionally, such closo-carborane salts can include any one or more of the pendant groups described above. For example, in various embodiments of the present invention, the cage compound employed can comprise a closo-carborane salt having the general formula R[CB_(n)H_(n)]X, where n can be in the range of from 6 to 11, X can be any of a variety of cationic species, and where R can be any of the pendant groups mentioned above. For instance, R can be chosen from aliphatic compounds (e.g., n-hexyl) and/or heteroatom-containing aliphatic compounds.

In various embodiments of the present invention, the cage compound employed can comprise a closo-borane salt having the general formula [B_(n)H_(n)]X₂, where n can be in the range of from 7 to 12, and X can be any of a variety of cationic species. Cationic species suitable for use as X include, but are not limited to, Li⁺, Na⁺, K⁺, Cs⁺, and NR₄ ⁺ (where R is hydrogen or an aliphatic group, for example). Additionally, in various embodiments, the cage compound employed can comprise a closo-borane having the general formula [B_(n)H₂]X₂, where n is 12 (i.e., a dodecaborate), and X can be any variety of cationic species. Furthermore, such closo-boranes can include any one or more of the pendant groups described above. It should be noted that, although certain compounds described herein employ two monocationic species to form a salt, it is contemplated in various embodiments of the present invention to employ multicationic species (e.g., dications) in combination with cage compounds that are multianionic (e.g., dianionic). For instance, dicationic species contemplated for use herein include, but are not limited to, alkaline earth metals, such as magnesium, calcium, and the like.

In various embodiments of the present invention, the cage compound employed can comprise a closo-borane salt having the general formula [B_(n)H_(m)(OR)_(p)]X₂, where each R can individually be hydrogen atoms and/or or aliphatic groups (e.g., a methyl or ethyl group), where n can be in the range of from 7 to 12, where m+p=n, with p being in the range of from 1 to 12, or in the range of from 2 to 12, and X can be any of a variety of cationic species, including, but not limited to, Li⁺, Na⁺, K⁺, Cs⁺, and NR₄ ⁺ (where R is hydrogen or an aliphatic group, for example). Furthermore, such closo-boranes can include any one or more of the pendant groups described above.

In various embodiments of the present invention, the cage compound employed can comprise a nido-carborane salt having the general formula R_(x)[C₂B_(n)H_(n+2−x)]X₂ where x is in the range of from 1 to 2, where n is in the range of from 5 to 9, and where each R can be the same or different, and can independently comprise any of the pendant groups mentioned above. For instance, R can be chosen from aliphatic compounds (e.g., n-hexyl) and/or heteroatom-containing aliphatic compounds. X can be any of a variety of cationic species, including, but not limited to, Li⁺, Na⁺, K⁺, Cs⁺, and NR₄ ⁺ (where R is hydrogen or an aliphatic group, for example). In one or more embodiments, n can be 9, giving the general formula R_(x)[C₂B₉H_(11−x)]X₂ where x is in the range of from 1 to 2, where each R can be the same or different, and can independently comprise any of the pendant groups mentioned above, and where X can be any of a variety of cationic species, including, but not limited to, Li⁺, Na⁺, K⁺, Cs⁺, and NR₄ ⁺ (where R is hydrogen or an aliphatic group, for example).

In various embodiments of the present invention, the cage compound employed can comprise a nido-carborane salt having the general formula R_(x)[CB_(n)H_(n+1−x)]X₃ where x is in the range of from 0 to 1, where n is in the range of from 6 to 10, and where R can comprise any of the pendant groups mentioned above. For instance, R can be chosen from aliphatic compounds (e.g., n-hexyl) and/or heteroatom-containing aliphatic compounds. X can be any of a variety of cationic species, including, but not limited to, Li⁺, Na⁺, K⁺, Cs⁺, and NR₄ ⁺ (where R is hydrogen or an aliphatic group, for example). In one or more embodiments, n can be 10, giving the general formula R_(x)[CB₁₀H_(11−x)]X₃ where x is in the range of from 0 to 1, where R can comprise any of the pendant groups mentioned above, and where X can be any of a variety of cationic species, including, but not limited to, Li⁺, Na⁺, K⁺, Cs⁺, and NR₄ ⁺ (where R is hydrogen or an aliphatic group, for example).

As noted above, in various embodiments of the present invention, the cage compound employed can comprise a structure having two or more cage compounds linked together by a linking group. Such a linking group can be any multivalent group capable of linking two or more cage compounds together. In one or more embodiments, the linking group can be an alkylene or arylene group. As used herein, the term “alkylene” shall denote a divalent group formed by removing two hydrogen atoms from a hydrocarbon, the free valencies of which are not engaged in a double bond, and may include heteroatoms. As used herein, the term “arylene” shall denote a divalent group formed by removing two hydrogen atoms from a ring carbon in an arene (i.e., a mono- or polycyclic aromatic hydrocarbon), and may include heteroatoms. Linking alkylene and arylene groups suitable for use include any substituted or unsubstituted C₁ to C₂₀ alkylene or arylene groups. Additionally, alkylene groups suitable for use can be straight, branched, or cyclic, and can be saturated or unsaturated. In one or more embodiments, the linking groups can comprise a straight-chain C₁ to C₁₂ alkylene group. In still other embodiments, the linking group can be selected from the group consisting of 1,2-ethylene, 1,3-n-propylene, and 1,4-n-butylene. Additionally, aliphatic and aromatic groups, including heteroatom-substituted aliphatic and aromatic groups, having more than two free valencies can be employed as linking groups.

In various embodiments, the cage compound can comprise one or more of the compounds shown in formulas (I) through (XV), below. It should be noted that, for ease of reference, all borane and carborane structures depicted herein are shown without the hydrogen atoms that are normally covalently bound to cage atoms. In general, unless otherwise substituted, each cage atom in a borane or carborane cage compound having a closo-configuration will be covalently bound to one hydrogen atom.

In one or more embodiments of the present invention, the cage compound can comprise one or more alkyl o-carboranes having the following structure (I):

where R is an alkyl or aryl group. Suitable alkyl and aryl groups for use as R of structure (I) can be any substituted or unsubstituted C₁ to C₂₀ alkyl or aryl groups, and may include heteroatoms. Additionally, alkyl groups suitable for use as R of structure (I) can be straight, branched, or cyclic, and can be saturated or unsaturated. Examples of suitable alkyl substituents include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-decyl, n-dodecyl, cyclopentyl, and cyclohexyl groups. In various embodiments, R of structure (I) can be n-hexyl.

In one or more embodiments of the present invention, the cage compound can comprise one or more 1,2-bis-(hydroxymethyl)-carboranes (“carborane diol”) having the following structure (II):

In one or more embodiments of the present invention, the cage compound can comprise one or more epoxy-containing carboranes having either of the following structures (III) or (IV):

where R¹ and R² of formulas (III) and (IV) can independently be any substituted or unsubstituted alkylene or arylene groups having a carbon number of from 1 to 20, and may include heteroatoms. Additionally, alkylene groups suitable for use as R¹ and R² can be straight, branched, or cyclic, and can be saturated or unsaturated. In one or more embodiments, R¹ and R² can independently be straight-chain C₁ to C₁₂ alkylene groups. Additionally, R¹ and R² can independently be saturated, unsubstituted, straight-chain C₁ to C₉ alkylene groups. Examples of suitable alkylene groups include, but are not limited to, methylene, ethylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, octamethylene, nonamethylene, decamethylene, and dodecamethylene groups. It should be noted that regardless of the composition and configuration of the R¹ and R² groups, the epoxy groups shown in formulas (III) and (IV) can be covalently bound to any terminal or non-terminal carbon atom present in the R¹ and R² groups. In one or more embodiments, the epoxy groups can be covalently bound to the terminal carbon atom of the R¹ and R² groups. Additionally, in various embodiments, R¹ and R² in formula (IV) can comprise alkylene or arylene groups having like structures. In one or more embodiments, R¹ and R² are each methylene groups in formulas (III) and (IV).

In one or more embodiments of the present invention, the cage compound can comprise one or more silyl-containing carboranes having the following structure (V):

where R¹ of formula (V) can be any substituted or unsubstituted alkylene or arylene group having a carbon number of from 1 to 20, and may include heteroatoms. Additionally, alkylene groups suitable for use as R¹ can be straight, branched, or cyclic, and can be saturated or unsaturated. In one or more embodiments, R¹ can be a straight-chain C₁ to C₁₂ alkylene group. Additionally, R¹ can be a saturated, unsubstituted, straight-chain C₁ to C₉ alkylene group. Examples of suitable alkylene groups include, but are not limited to, methylene, ethylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, octamethylene, nonamethylene, decamethylene, and dodecamethylene groups. It should be noted that regardless of the composition and configuration of the R¹ group, the silyl group shown in formula (V) can be covalently bound to any terminal or non-terminal carbon atom present in the R¹ group. In one or more embodiments, the silyl group can be covalently bound to the terminal carbon atom of the R¹ group. In one or more embodiments, R¹ is a trimethylene group (i.e., a divalent n-propyl group). R³, R⁴, and R⁵ of formula (V) can be independently-chosen alkyl or aryl groups, optionally comprising heteroatoms. Suitable alkyl or aryl groups for use as R³, R⁴, and R⁵ of formula (V) can be any substituted or unsubstituted C₁ to C₂₀ alkyl or aryl groups. Additionally, alkyl groups suitable for use as R³, R⁴, and R⁵ of formula (V) can be straight, branched, or cyclic, and can be saturated or unsaturated. Examples of suitable alkyl substituents include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-decyl, n-dodecyl, cyclopentyl, and cyclohexyl groups. In various embodiments, R², R³, and R⁴ of formula (V) are each ethyl groups.

In one or more embodiments of the present invention, the cage compound can comprise one or more isocyanate-containing carboranes having either of the following structures (VI) or (VII):

where R¹ and R² of formulas (VI) and (VII) can independently be any substituted or unsubstituted alkylene or arylene groups having a carbon number of from 1 to 20, and may include heteroatoms. Additionally, alkylene groups suitable for use as R¹ and R² can be straight, branched, or cyclic, and can be saturated or unsaturated. In one or more embodiments, R¹ and R² can independently be straight-chain C₁ to C₁₂ alkylene groups. Additionally, R¹ and R² can independently be saturated, unsubstituted, straight-chain C₁ to C₉ alkylene groups. Examples of suitable alkylene groups include, but are not limited to, methylene, ethylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, octamethylene, nonamethylene, decamethylene, and dodecamethylene groups. It should be noted that regardless of the composition and configuration of the R¹ and R² groups, the isocyanate groups shown in formulas (VI) and (VII) can be covalently bound to any terminal or non-terminal carbon atom present in the R¹ and R² groups. In one or more embodiments, the isocyanate groups can be covalently bound to the terminal carbon atom of the R¹ and R² groups. Additionally, in various embodiments, R¹ and R² in formula (VI) can comprise alkylene or arylene groups having like structures. In one or more embodiments, R¹ and R² are each methylene, ethylene, trimethylene, tetramethylene, or pentamethylene groups in formulas (VI) and (VII).

In one or more embodiments of the present invention, the cage compound can comprise one or more primary amine-containing carboranes having any of the following structures (VIII), (IX), (X), or (XI):

where R¹ and R² of formulas (VIII)-(XI) can independently be any substituted or unsubstituted alkylene or arylene groups having a carbon number of from 1 to 20, and may include heteroatoms. Additionally, alkylene groups suitable for use as R¹ and R² can be straight, branched, or cyclic, and can be saturated or unsaturated. In one or more embodiments, R¹ and R² can independently be straight-chain C₁ to C₁₂ alkylene groups. Additionally, R¹ and R² can independently be saturated, unsubstituted, straight-chain C₁ to C₉ alkylene groups. Examples of suitable alkylene groups include, but are not limited to, methylene, ethylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, octamethylene, nonamethylene, decamethylene, and dodecamethylene groups. It should be noted that regardless of the composition and configuration of the R¹ and R² groups, the amine groups shown in formulas (VIII)-(XI) can be covalently bound to any terminal or non-terminal carbon atom present in the R¹ and R² groups. In one or more embodiments, the isocyanate groups can be covalently bound to the terminal carbon atom of the R¹ and R² groups. Additionally, in various embodiments, R¹ and R² in formulas (IX) and (XI) can comprise alkylene or arylene groups having like structures. In one or more embodiments, R¹ and R² are each methylene, ethylene, trimethylene, tetramethylene, or pentamethylene groups in formulas (VIII)-(XI).

In one or more embodiments of the present invention, the cage compound can comprise one or more linked (a.k.a., “tethered”) carboranes having the following structure (XII):

where R¹ of formula (XII) can be any substituted or unsubstituted alkylene or arylene group having a carbon number of from 1 to 20, and may include heteroatoms. Additionally, alkylene groups suitable for use as R¹ can be straight, branched, or cyclic, and can be saturated or unsaturated. In one or more embodiments, R¹ can be a straight-chain C₁ to C₁₂ alkylene group. Additionally, R¹ can be a saturated, unsubstituted, straight-chain C₁ to C₉ alkylene group. Examples of suitable alkylene groups include, but are not limited to, methylene, ethylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, octamethylene, nonamethylene, decamethylene, and dodecamethylene groups. It should be noted that regardless of the composition and configuration of the R¹ group, the carboranes shown in formula (XII) can be covalently bound to any terminal or non-terminal carbon atom present in the R¹ group. In one or more embodiments, the carboranes can be covalently bound to the respective terminal carbon atoms of the R¹ group. In one or more embodiments, R¹ is a trimethylene group (i.e., a divalent n-propyl group), thus forming a 1,3-di-o-carboranylpropane. Additionally, though not depicted, the linked carborane of formula (XII) may contain one or more of the pendant groups discussed above, which can, but need not be, covalently bound to either of the un-linked carbon cage atoms in formula (XII).

In one or more embodiments of the present invention, the cage compound can comprise one or more borane salts having the following structure (XIII):

where X is any cationic species. In one or more embodiments, X can be selected from the group consisting of Li⁺, Na⁺, K⁺, Cs⁺, and quaternary ammonium cations. In various embodiments, X is Li⁺, thus providing a lithium dodecaborate (i.e., Li₂[B₁₂H₁₂]).

In one or more embodiments of the present invention, the cage compound can comprise one or more hydroxylated borane anions or salts thereof having either of the following structures (XIV) or (XV):

where X is any cationic species and n is in the range of from 1 to 11. In one or more embodiments, X can be selected from the group consisting of Li⁺, Na⁺, K⁺, Cs⁺, and quaternary ammonium cations. In various embodiments, X is Li⁺. In one or more embodiments, n can be 1. In other various embodiments, n can be 11. Additionally, when n is 1, each of the boranes in formulas (XIV) and (XV) can be in the ortho- (i.e., 1,2-bis-hydroxy dodecaborane), meta- (i.e., 1,7-bis-hydroxy dodecaborane), or para- (i.e., 1,12-bis-hydroxy dodecaborane) configuration. In various embodiments, when n is 1, the boranes of formulas (XIV) and (XV) are in the ortho-configuration. In other various embodiments, when n is 1, the boranes of formulas (XIV) and (XV) are in the meta-configuration.

In one or more embodiments of the present invention, the cage compound or compounds selected for use can comprise less than 95, less than 90, less than 85, less than 80, less than 75, less than 70, less than 65, less than 60, less than 55, less than 50, less than 45, less than 40, less than 35, less than 30, less than 25, less than 20, less than 15, less than 10, less than 5, or less than 1 weight percent of ortho-[1,2-dicarbadodecaborane], based on the entire weight of cage compounds present in the composition. Additionally, in various embodiments, the cage compound or compounds selected for use can comprise no or substantially no ortho-[1,2-dicarbadodecaborane]. As used herein, the term “substantially no,” when used with respect to cage compound components, shall denote a content of no more than 10 parts per million by weight (“ppmw”).

In one or more embodiments of the present invention, the cage compound or compounds selected for use can comprise less than 95, less than 90, less than 85, less than 80, less than 75, less than 70, less than 65, less than 60, less than 55, less than 50, less than 45, less than 40, less than 35, less than 30, less than 25, less than 20, less than 15, less than 10, less than 5, or less than 1 weight percent of meta-[1,7-dicarbadodecaborane], based on the entire weight of cage compounds present in the composition. Additionally, in various embodiments, the cage compound or compounds selected for use can comprise no or substantially no meta-[1,7-dicarbadodecaborane].

In one or more embodiments of the present invention, the cage compound or compounds selected for use can comprise less than 95, less than 90, less than 85, less than 80, less than 75, less than 70, less than 65, less than 60, less than 55, less than 50, less than 45, less than 40, less than 35, less than 30, less than 25, less than 20, less than 15, less than 10, less than 5, or less than 1 weight percent of para-[1,12-dicarbadodecaborane], based on the entire weight of cage compounds present in the composition. Additionally, in various embodiments, the cage compound or compounds selected for use can comprise no or substantially no para-[1,12-dicarbadodecaborane].

In one or more embodiments of the present invention, the cage compound or compounds selected for use can comprise less than 95, less than 90, less than 85, less than 80, less than 75, less than 70, less than 65, less than 60, less than 55, less than 50, less than 45, less than 40, less than 35, less than 30, less than 25, less than 20, less than 15, less than 10, less than 5, or less than 1 weight percent of a compound having the following structure (XVI):

where R is an n-alkyl group, based on the entire weight of cage compounds present in the composition. Additionally, in various embodiments, the cage compound or compounds selected for use can free or substantially free of any compounds having the structure (XVI), where R is an n-alkyl group. As used herein the term “substantially free” shall denote a content of no more than 10 ppmw.

In addition to the above-described cage compounds, the filler can comprise one or more additional materials. In various embodiments, the filler can further comprise one or more materials selected from the group consisting of carbon nanotubes, carbon fullerenes, polyhedral oligomeric silsesquioxane, boron nitride nanotubes, clay, and mixtures of two or more thereof. In various embodiments, such additional materials can, in combination, constitute up to 95, up to 85, up to 75, up to 65, or up to 50 weight percent of the filler.

As noted above, nanocomposites according to various embodiments of the present invention can comprise a matrix. The matrix employed as a component in the nanocomposite can comprise a polymer. The term “polymer,” as used herein and unless otherwise specified, is intended to include homopolymers and polymers containing two or more types of monomer residues (e.g., copolymers, terpolymers, etc.). The polymer or combination of polymers employed can constitute at least 50 weight percent, at least 60 weight percent, at least 70 weight percent, at least 80 weight percent, at least 90 weight percent, or at least 99 weight percent of the matrix. In various embodiments, the polymer or combination of polymers can constitute all or substantially all of the matrix. As used herein, the term “substantially all,” with respect to the polymeric concentration of the matrix, shall mean that the matrix comprises at most 10 ppmw of non-polymeric material.

Any polymer known or hereafter discovered in the art can be employed in the various embodiments of the present invention. In one or more embodiments, as described in greater detail below, the polymer can be chosen so that it does not form covalent bonds with the above-described cage compound chosen for use in the nanocomposite. Furthermore, in various embodiments, the polymer is not a sacrificial binder. Types of polymers suitable for use in various embodiments of the present invention include, but are not limited to, an epoxy polymer, polyurethane, silicone (i.e., polysiloxane), polyethylene-co-vinyl acetate) (“EVA”), poly(ethylene-co-vinyl acetate-co-vinyl alcohol) (“EVA-OH”), poly(ethylene-co-ethyl acrylate) (“PEEA”), poly(ethylene-co-octene) (“PEO”), styrene-butadiene-styrene triblock copolymers (“SBS”), poly(conjugated dienes) (e.g., polybutadiene, polyisoprene, etc.), polycyanurate, polyacetal, polyacrylic, polycarbonate, polystyrene, polyester, polyamide, polyamideimide, polyarylate, polyarylsulfone, polyethersulfone, polyphenylene sulfide, polyvinyl chloride, polysulfone, polyimide, polyetherimide, polytetrafluoroethylene, polyetherketone, polyether etherketone, polyether ketone ketone, polybenzoxazole, polyoxadiazole, polybenzothiazinophenothiazine, polybenzothiazole, polypyrazinoquinoxaline, polypyromellitimide; polyquinoxaline, polybenzimidazole, polyoxindole, polyoxoisoindoline, polydioxoisoindoline, polytriazine, polypyridazine, polypiperazine, polypyridine, polypiperidine, polytriazole, polypyrazole, polypyrrolidine, polycarborane, polyoxabicyclononane, polydibenzofuran, polyphthalide, polyacetal, polyanhydride, polyvinyl ether, polyvinyl thioether, polyvinyl alcohol, polyvinyl ketone, polyvinyl halide, polyvinyl nitrile, polyvinyl ester, polysulfonate, polysulfide, polythioester, polysulfone, polysulfonamide, polyurea, polyphosphazene, polysilazane, phenolic resin, or combinations of two or more thereof. In one or more embodiments, the matrix can comprise a polymer selected from the group consisting of an epoxy polymer, a polyurethane, poly(ethylene-co-vinyl acetate), poly(ethylene-co-vinyl acetate-co-vinyl alcohol), poly(ethylene-co-ethyl acrylate), poly(ethylene-co-octene), a polycyanurate, and mixtures of two or more thereof. In other various embodiments, the polymer can be selected from the group consisting of an epoxy polymer, a polyurethane, a polysiloxane, poly(ethylene-co-vinyl acetate), poly(ethylene-co-vinyl acetate-co-vinyl alcohol), styrene-butadiene-styrene, poly(ethylene-co-ethyl acrylate), poly(ethylene-co-octene), a polycyanurate, and mixtures of two or more thereof. Additionally, in various embodiments, the matrix can comprise a plurality of polymer types. As used herein, the term “plurality” shall mean two or more.

In one or more embodiments, the matrix can comprise a polymer having one or more residues of a cage compound monomer, such as a borane cage compound monomer, a carborane cage compound monomer, or mixtures thereof. In various embodiment, the matrix can comprise a polymer or polymers having one or more cage compound monomer residues in an amount of at least 10, at least 20, at least 30, at least 40, at least 50, at least 60, at least 70, at least 80, at least 90, or at least 99 weight percent. In various embodiments, the matrix can further comprise a polymer in addition to the polymer having one or more residues of a cage compound monomer selected from the group consisting of an epoxy polymer, a polyurethane, a polysiloxane, poly(ethylene-co-vinyl acetate), poly(ethylene-co-vinyl acetate-co-vinyl alcohol), styrene-butadiene-styrene, poly(ethylene-co-ethyl acrylate), poly(ethylene-co-octene), a polycyanurate, and mixtures of two or more thereof. When the matrix comprises a polymer or polymers in addition to polymers containing cage compound monomer residues, such additional polymer or polymers can constitute at least 10, at least 20, at least 30, at least 40, at least 50, at least 60, at least 70, at least 80, at least 90, or at least 99 weight percent of the matrix. Furthermore, cage compound-containing polymers can be present in a weight ratio with non-cage compound containing polymers in the range of from about 99:1 to about 1:99, in the range of from about 1:50, to about 50:1, in the range of from about 1:10 to about 10:1, or in the range of from about 1:2 to about 2:1.

Cage compound monomers can be any of those cage compounds described above as being suitable for use in the filler. For instance, in various embodiments, the selected cage compound monomer can comprise 12 cage atoms and have an icosahedral structure. Additionally, in various embodiments, the cage compound monomer can comprise at least one or at least two reactive functional groups per cage compound. Such reactive functional groups include, but are not limited to, hydroxy, carboxy, epoxy, isocyanate, primary amine, silyl, and alkoxy silyl. In one or more embodiments, the cage compound monomer can be selected from the group consisting of:

and mixtures of two or more thereof, where R¹ and R² of the immediately foregoing formulas can independently be any substituted or unsubstituted alkylene or arylene groups having a carbon number of from 1 to 20, and may include heteroatoms. Additionally, alkylene groups suitable for use as R¹ and R² can be straight, branched, or cyclic, and can be saturated or unsaturated. In one or more embodiments, R¹ and R² can independently be straight-chain C₁ to C₁₂ alkylene groups. Additionally, R¹ and R² can independently be saturated, unsubstituted, straight-chain C₁ to C₉ alkylene groups. Examples of suitable alkylene groups include, but are not limited to, methylene, ethylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, octamethylene, nonamethylene, decamethylene, and dodecamethylene groups. It should be noted that regardless of the composition and configuration of the R¹ and R² groups, the functional groups shown in the immediately foregoing formulas can be covalently bound to any terminal or non-terminal carbon atom present in the R¹ and R² groups. In one or more embodiments, the functional groups can be covalently bound to the terminal carbon atom of the R¹ and R² groups. Additionally, in various embodiments, R¹ and R² in any of the immediately foregoing formulas can comprise alkylene or arylene groups having like structures. In one or more embodiments, R¹ and R² are each methylene, ethylene, trimethylene, tetramethylene, or pentamethylene groups. R³, R⁴, and R⁵ of the immediately foregoing formulas can be independently-chosen alkyl groups. Suitable alkyl groups for use as R³, R⁴, and R⁵ include, but are not limited to, any substituted or unsubstituted C₁ to C₂₀ alkyl groups. Additionally, alkyl groups suitable for use as R³, R⁴, and R⁵ in the immediately foregoing formulas can be straight, branched, or cyclic, and can be saturated or unsaturated. Examples of suitable alkyl substituents include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-decyl, n-dodecyl, cyclopentyl, and cyclohexyl groups. In various embodiments, R², R³, and R⁴ of the foregoing formulas are each ethyl groups. Furthermore, X in the immediately foregoing formulas can be any cationic species. In one or more embodiments, X can be selected from the group consisting of Li⁺, Na⁺, K⁺, Cs⁺, and quaternary ammonium cations. In various embodiments, X can be Li⁺. Additionally, n of formulas (XIV) and (XV) can be in the range of from 1 to 11. In various embodiments, n can of formulas (XIV) and (XV) can be 1 or 11.

Polymers containing cage compound monomer residues can contain such residues in the polymer backbone, pendant to the polymer backbone, and/or in crosslinked polymer networks. Additionally, polymers containing cage compound monomer residues can be homopolymers of cage compound monomer residues, copolymers of two or more types of cage compound monomer residues, or copolymers of one or more types of cage compound monomer residues with one or more other types of monomer residues. Examples of additional monomers that can be combined with cage compound monomers include, but are not limited to, bisphenol A diglycidyl ether (“BADGE”), 4,4′-methylenedianiline (“MDA”), nonyl phenol, 1-(2-aminoethyl)piperazine, diethylenetriamine, triethylenetriamine, a bisisocyanate, a bishydroxy (e.g., an aliphatic diol), and mixtures of two or more thereof. Additionally, cage compound monomers can be incorporated into existing polymers via grafting or pendant attachment. Examples of such existing polymers include, but are not limited to, EVA-OH and toluenediisocyanate end-capped polybutadiene (“TDI end-capped PBD”),

In one or more embodiments of the present invention, the polymer or polymers selected for use can comprise less than 95, less than 90, less than 85, less than 80, less than 75, less than 70, less than 65, less than 60, less than 55, less than 50, less than 45, less than 40, less than 35, less than 30, less than 25, less than 20, less than 15, less than 10, less than 5, or less than 1 weight percent of 1,4-polybutadiene, based on the entire weight of polymers present in the composition. Additionally, in various embodiments, the polymer or polymers selected for use can comprise no or substantially no 1,4-polybutadiene. As used herein, the term “substantially no,” when used with respect to polymeric components of the matrix, shall denote a content of no more than 10 ppmw.

In one or more embodiments of the present invention, the polymer or polymers selected for use can comprise less than 95, less than 90, less than 85, less than 80, less than 75, less than 70, less than 65, less than 60, less than 55, less than 50, less than 45, less than 40, less than 35, less than 30, less than 25, less than 20, less than 15, less than 10, less than 5, or less than 1 weight percent of a poly(conjugated diene), based on the entire weight of polymers present in the composition. Additionally, in various embodiments, the polymer or polymers selected for use can comprise no or substantially no poly(conjugated diene). In embodiments where the polymer or polymers selected for use contain less than a certain amount of poly(conjugated diene), the term “poly(conjugated diene)” is intended to denote a homopolymer of conjugated diene monomer residues. Thus, copolymers containing conjugated diene monomer residues in conjunction with other types of monomer residues are not intended to be limited by the foregoing. For instance, copolymers such as, for example, styrene-butadiene-styrene, are not intended to be included as a “poly(conjugated diene),” even though such a copolymer may have poly(conjugated diene) (i.e., polybutadiene) segments.

In one or more embodiments of the present invention, the polymer or polymers selected for use can comprise less than 95, less than 90, less than 85, less than 80, less than 75, less than 70, less than 65, less than 60, less than 55, less than 50, less than 45, less than 40, less than 35, less than 30, less than 25, less than 20, less than 15, less than 10, less than 5, or less than 1 weight percent of a polysiloxane, based on the entire weight of polymers present in the composition. Additionally, in various embodiments, the polymer or polymers selected for use can comprise no or substantially no polysiloxane.

As noted above, nanocomposites can be prepared from combinations of one or more of the above-described matrices and fillers. In one or more embodiment, nanocomposites can comprise at least one cage compound that is not covalently bound to at least one polymer. In other embodiments, the nanocomposites can comprise at least one cage compound that is not covalently bound to any polymer present in the nanocomposite. Thus, in various embodiments, polymer and cage compound combinations can be chosen according to their relative reactivity towards each other. In one or more embodiments, at least one polymer can be chosen that is non-reactive with respect to at least one chosen cage compound. Conversely, at least one cage compound can be chosen that is non-reactive with respect to at least one chosen polymer. As used herein, the term “non-reactive” shall denote a polymer and cage compound combination that does not form a new molecular structure via covalent bonding when combined alone (e.g., in the absence of catalysts, polymerization initiators, etc.) at standard temperature and pressure according to the National Institute of Standards and Technology (i.e., 20° C., 1 atm). In various embodiments, at least one cage compound does not covalently bound to at least one polymer at a temperature in the range of from −100 to 250° C. and a pressure from 0.01 to 20 atm when combined alone.

Nanocomposites according to various embodiments of the present invention include any combination of at least one cage compound (i.e., as part or all of a filler) and at least one polymer (i.e., as part or all of a matrix) described above, with the proviso that at least one cage compound is not covalently bound to at least one polymer. Specific examples of suitable combinations of polymers and cage compounds include, but are not limited to, (a) a matrix comprising an epoxy polymer and/or a polyurethane and a filler comprising n-hexyl-o-carborane; (b) a matrix comprising an epoxy polymer combined with a carboranyl bisepoxide (e.g., formula (IV), above) and a filler comprising n-hexyl-o-carborane; (c) a matrix comprising EVA and/or EVA-OH polymers and a filler comprising at least one cage compound selected from the group consisting of lithium dodecaborate (i.e., Li₂ ²⁺[B₁₂H₁₂]²⁻; formula (XIII), above), tethered carborane (i.e., formula (XII), above), carborane diol (i.e., formula (II), above), n-hexyl-o-carborane (i.e., formula (I), above), cesium dodecaborate (i.e., Cs₂ ²⁺[B₁₂H₁₂]²⁻; formula (XIII), above), potassium dodecaborate (i.e., K₂ ²⁺[B₁₂H₁₂]²⁻; formula (XIII), above), ditetramethylammonium dodecaborate (i.e., [(CH₃)₄N]₂ ²⁺[B₁₂H₁₂]²⁻; formula (XIII), above), ditetramethylammonium dodecahydroxy borane (i.e., [(CH₃)₄N]₂ ²⁺[B₁₂(OH)₁₂]²⁻; formula (XV), above), lithium dodecahydroxy borane (i.e., Li₂ ²⁺[B₁₂(OH)₁₂]²⁻; formula (XV), above), and mixtures of two or more thereof; (d) a matrix comprising PEEA polymer and a filler comprising at least one cage compound selected from the group consisting of lithium dodecaborate, tethered carborane, diol carborane, n-hexyl-o-carborane, and mixtures of two or more thereof; and (e) a matrix comprising PEO polymer and a filler comprising at least one cage compound selected from the group consisting of lithium dodecaborate, tethered carborane, diol carborane, n-hexyl-o-carborane, and mixtures of two or more thereof.

The nanocomposites described herein can comprise any desired amounts or ratios of matrix and filler. In various embodiments, the filler can be present in the nanocomposite in an amount of at least 0.01, at least 0.1, or at least 0.25 weight percent, based on the entire weight of the nanocomposite. Additionally, in one or more embodiments, the filler can be present in the nanocomposite in an amount in the range of from about 0.01 to about 75 weight percent, in the range of from about 0.1 to about 50 weight percent, or in the range of from 0.25 to 30 weight percent, based on the entire weight of the nanocomposite. In various embodiments; the matrix can be present in the nanocomposite in an amount of at least 25 weight percent, at least 50 weight percent, or at least 70 weight percent. Furthermore, the matrix can be present in the nanocomposite in an amount in the range of from about 50 to about 99.99 weight percent, in the range of from about 60 to about 99.9 weight percent, or in the range of from 70 to 99.75 weight percent.

The addition of the various cage compounds described above can have varying effects on the polymer employed in the matrix of the nanocomposite, depending on the type of polymer chosen as well as the type of cage compound chosen. In various embodiments, the selected cage compound can have a plasticizing effect on the chosen polymer. Thus, in such embodiments, the nanocomposite can have a lower glass transition temperature (“Tg”) compared to the un-modified matrix polymer or polymers. In alternate embodiments, the selected cage compound can have a reinforcing effect on the chosen polymer. Thus, in such embodiments, the nanocomposite can have a higher Tg compared to the un-modified matrix polymer or polymers. It should be noted that the Tg for a given polymer or for a given phase within a polymer composite or mixture, the exact temperature of which may depend on the method used in its determination, is the temperature about which the polymer changes from a rigid, glassy solid to an amorphous elastomeric material. In general, this temperature is closely associated with the tan δ peak maximum for the same material. The tan δ peak maximum is the ratio of the loss modulus (G″) and storage modulus (G′) of a given polymer or a given phase within a polymer composite or mixture.

In another embodiment, the filler can be used to reinforce the polymer (and thus products containing the polymer) in a way that can be adjusted at a later point in time. In this instance, a hygroscopic salt is present in the filler. Preferably, the filler consists essentially of, and even more preferably consists of, the hygroscopic salt. The preferred hygroscopic salt can be any of the cage compounds discussed previously, with the most preferred cage compounds being those described above having the general formula [B_(n)H_(n)]X₂ (with the variables as defined previously). In the most preferred such compound, X is Li, and even more preferably n is also 12.

As noted above, the hygroscopic salt can be used to fine-tune the properties of a polymer or polymer mixture, with the polymer or polymer mixtures being the same as those described above. In some embodiments, using a filler comprising this salt will increase the glass transition temperature dramatically. Typical increases will be at least about 5° C., preferably at least about 10° C., and more preferably from about 10° C. to about 100° C. This will cause the polymer-filler composition, as well as products formed from the polymer-filler composition, to be quite rigid.

When the need arises to cause the composition or product to become less rigid or more flexible, it can be stored in an undessicated environment or otherwise exposed to moisture, and the salt will cause moisture to be absorbed into the composition or product. That moisture will act as a plasticizer, and the material will become more flexible as water is absorbed. Specifically, the glass transition temperature will drop from that of the rigid composition or product (i.e., right after reinforcement but before moisture exposure). In some embodiments, the level of drop will be at least about 1° C., at least about 10° C., from about 10° C. to about 100° C., and from about 30° C. to about 100° C. Preferably, this difference in glass transition temperatures will be observed within about 1 day after exposure to moisture was begun for at least about 1° C., within about 1 day for at least about 10° C., within about 7 days for 10-100° C., and within about 28 days for 30-100° C. This drop and time frame would be typical in a sample having a surface area of about 3×10⁻⁴ m². It will be appreciated that the drop would (approximately) proportionately increase as the surface area of the sample increased.

Furthermore, the storage modulus will drop from that of the rigid composition or product (i.e., right after reinforcement but before moisture exposure). The storage modulus at room temperature after 1 day of exposure to ambient moisture will drop at least about 40%, preferably at least about 55%, and more preferably from about 70% to about 90% of the storage modulus immediately prior to when moisture exposure was begun. The storage modulus at 0° C. after 1 day of exposure to ambient moisture will drop at least about 30%, preferably at least about 45%, and more preferably from about 60% to about 85%. Finally, the storage modulus at −25° C. after 1 day of exposure to ambient moisture will drop at least about 10%, preferably at least about 15%, and more preferably from about 20% to about 30%. These effects (both glass transition temperature and storage modulus changes) can be reversed by drying the product, thus returning it to its former rigid state.

It will be appreciated that this ability to fine-tune the composition allows it to find use in a number of applications, including any application in which the particular polymer(s) would normally be used. Some examples of such articles of manufacture include technical moldings and extrudates, tires, seals, o-rings, gaskets, cable sheathing and insulation, cellular rubber goods (foams and cushions), footwear soles, padding for sports equipment, floatation devices, waterproofing sheets, strips, flooring, cables, membranes, adhesives, glues, paints, coatings, biomedical engineering applications as a drug delivery device, encapsulation material for electronic and photovoltaic devices, and separator for HEPA filters. These compositions can be used for any cured elastomer application requiring weather resistance, ozone resistance, light resistance, hot air resistance, low compression set, neutron and radiation resistance, and/or controlled glass transition temperatures.

In addition to plasticization or reinforcement, the use of cage compounds can affect other properties of the matrix polymer. In various embodiments, the nanocomposite can have a higher storage and/or loss modulus compared to the un-modified matrix polymer or polymers. Alternatively, the nanocomposite can have a lower storage and/or loss modulus compared to the un-modified matrix polymer or polymers. In various embodiments, the nanocomposite can have an increased thermal stability compared to the un-modified matrix polymer or polymers. Alternatively, the nanocomposite can have decreased thermal stability compared to the un-modified matrix polymer or polymers. In various embodiments, the nanocomposite can have an increased melt viscosity compared to the un-modified matrix polymer or polymers. Alternatively, the nanocomposite can have decreased melt viscosity compared to the un-modified matrix polymer or polymers. In various embodiments, the nanocomposite can have an increased neutron absorption capability, particularly if the cage compound is enriched in ¹⁰B. As an example of such effects imparted by cage compound-containing fillers, lithium dodecaborate appears to reinforce, increase the thermal stability, storage and loss moduli, and melt viscosity of EVA-, EVA-OH-, and PEEA-containing matrices. Similarly, tethered carborane appears to slightly reinforce, increase the storage and loss moduli, and melt viscosity of EVA-, EVA-OH-, and PEEA-containing matrices. Also, carborane diol appears to slightly reinforce and increase the storage and loss moduli, but lowers the melt viscosity of EVA- and EVA-OH-containing matrices. Conversely, n-hexyl-o-carborane appears to plasticize, decrease the thermal stability, storage and loss moduli, and melt viscosity of EVA-, EVA-OH-, PEEA-, and PEO-containing matrices. In still other embodiments, the added cage compound can have little or no effect on the properties of the matrix polymer or polymers, even when present in large amounts. Furthermore, in one or more embodiments, the nanocomposites described herein can be effectively optically clear and colorless.

The nanocomposites described herein can be prepared employing any known or hereafter discovered methods in the art for preparing nanocomposite materials. In one or more embodiments, the nanocomposites can be prepared by simply combining and mixing a matrix comprising one or more of the above-described polymers with a filler comprising one or more of the above-described cage compounds. Any mixing methods known or hereafter discovered in the art can be employed for preparing the nanocomposites. Additionally, the nanocomposites can be prepared at a temperature in the range of from about −150 to about 200° C., in the range of from about −100 to about 150° C., or in the range of from −50 to 100° C. Furthermore, the nanocomposites can be prepared at a pressure in the range of from about 0.1 to about 20 atm, in the range of from about 0.5 to about 10 atm, or in the range of from 1 to 5 atm. After mixing, the mixture can optionally be cured for a period of time at room or elevated temperature. When elevated temperature is employed for curing the nanocomposite, such elevated temperature can be higher than the temperature employed for mixing the matrix and the filler. For instance, such elevated temperature can be at least 10, at least 50, or at least 100° C. higher than the temperature employed for mixing the matrix and the filler. In various embodiments, the curing temperature can be in the range of from about 50 to about 400° C., or in the range of from 75 to 150° C. Curing times can vary as needed. For example, curing times can be in the range of from about 30 minutes to about 1 week, or in the range of from 1 hour to 24 hours. When preparing the nanocomposites described herein, in various embodiments, at least one cage compound does not covalently bound to at least one polymer in the nanocomposite during the preparation procedure, including, but not limited to, during the mixing and curing steps described above.

The nanocomposites described herein can be used in a variety of applications, including preparation of articles of manufacture. Articles of manufacture employing one or more of the nanocomposites described herein may include, but are not limited to, tires, o-rings, gaskets, foams, cushions, pads, membranes, potting materials, adhesives, glues, paints, coatings, fibers, fabric coatings, and hoses, among others. Additionally, sensor applications, neutron shielding materials, electrospun fibers, or nanotubes containing one or more of the above-described nanocomposites are contemplated by various embodiments of the present invention. Furthermore, it is contemplated that such nanocomposites can be suited for use as part or all of drug delivery systems.

This invention can be further illustrated by the following examples of embodiments thereof, although it will be understood that these examples are included merely for the purposes of illustration and are not intended to limit the scope of the invention unless otherwise specifically indicated.

EXAMPLES Nanocomposites in Eva-Based Polymer Matrices Examples 1-6 Test Procedures for Examples 1-6

In the following Examples 1-6, nanocomposite test samples were subject to various characterization testing. The following procedures were employed.

AR-G2 Rheology Testing

A TA Instruments AR-G2 rheometer was used to determine rheological properties of samples using temperature sweep with a constant strain and frequency. The rheology testing was performed under torsion between 25 mm diameter parallel plates. As much as possible, disks (diameter ˜12.5 mm by ˜3.25 mm thick) of uniform size were used as samples. Using a 12.5 mm die, samples were cut from pressed sheets. All samples were subjected to a temperature sweep from high to low temperatures at strains of 0.05% and a frequency of 1 Hz. All experiments were performed under normal force control at 5.0 N, with a 0.5 N tolerance (gap=+/−500,000 nm). A temperature ramp rate of 5° C./minute was employed. The temperature range varied depending on the locations of the expected transitions, but for most uncured samples, samples were cooled from 30° C. to −60° C. at a rate of 5° C./minute. Higher initial temperatures were used for cured samples, and they were most often cooled from 100 to −60° C. A 5-10 minute equilibration time was used once a sample reached the starting temperature.

Rubber Process Analyzer RPA2000

A different type of rotational rheometer called a rubber process analyzer was used to determine the melt viscosity of the uncured EVA and EVA-OH nanocomposite samples above the melt point of the polymer. The RPA2000 instrument from Alpha Technologies determines the viscoelastic responses of materials by containing the sample (˜5 g) in a cavity formed by two dies. One of these dies oscillates through a rotational amplitude and the resulting sinusoidal torque is measured. A standard melt viscosity test was used to characterize uncured EVA and EVA-OH averages for complex viscosity, η*, over 5 minutes when tested at a temperature of 121° C., strain of 1° (14%), and frequency of 10 Hz.

Differential Scanning Calorimetry (“DSC”)

Differential scanning calorimetry was performed using a TA Instruments Q2000 DSC. All experiments were carried out on samples weighing between 7 mg and 15 mg using aluminum pans, and an identical, yet empty pan as a reference. During DSC analyses, all of the polymer nanocomposite samples were cooled from 25° C. to −100° C., heated to 150° C. or 200° C., cooled to −100° C., and reheated to 200° C. All cooling and heating rates used were 10° C./minute.

Thermogravimetric Analysis (“TGA”)

Thermogravimetric analyses were performed on clean platinum pans using a TA Instruments Q500 TGA. All experiments were performed using a ramp rate of 10° C./minute and heated up to 600° C. All experiments were performed under nitrogen.

Example 1 Preparation of EVA-Based Polymer Matrices

Three types of polyolefin elastomer systems were prepared to be incorporated with boron cage compounds (“BCC”): uncured poly(ethylene-co-vinyl acetate) (“EVA”), uncured poly(ethylene-co-vinyl acetate-co-vinyl alcohol) (“EVA-OH”), and poly(ethylene-co-vinyl acetate-co-vinyl alcohol) cured with diphenyl-4,4′-methylenebis(phenylcarbamate) (“cured EVA-OH”) via a urethane-type reaction.

EVA

The EVA polymer matrix, having a composition of 42% vinyl acetate and 58% ethylene was prepared by dissolving two EVA copolymers in toluene followed by precipitation in methanol. The EVA polymer matrix had the following structure:

The precipitated EVA blend was vacuum dried at 100° C. until solid sheets were formed and all of the solvents were removed. A formulation of 19 parts by weight EVATANE® 33-400 (33% vinyl acetate and 67% ethylene; available from Arkema, Inc.) and 81 parts by weight LEVAMELT® 456 (44% vinyl acetate and 56% ethylene; available from Lanxess Corp.) was used to obtain the EVA copolymer. The compositions of the individual EVAs and the 42% EVA blend were confirmed by titration (complete saponification with a known amount of base followed by back-titration with hydrochloric acid solution to determin the amount of base remaining) and proton nuclear magnetic resonance (“¹H NMR”) methods. ¹H NMR (400 MHz, CDCl₃): δ 4.7-5.0 (CH₂—CH), 1.9-2.2 (CH₃), 1.4-1.9 (CH ₂—CH), 0.7-1.4 (CH ₂—CH ₂).

EVA-OH

The EVA-OH polymer matrix was prepared by a base-catalyzed alcoholysis reaction of the EVA blend (whose preparation is described immediately above). To prepare the EVA-OH matrix, 100 parts by weight of the EVA polymer were dissolved in a solution of 250 parts by weight toluene, 45.4 parts by weight methanol, and 45.4 parts by weight ethanol. 4.62 parts by weight of 0.44 N alcoholic KOH solution (equal parts methanol and ethanol) were added to the solution, causing partial alcoholysis. A small percentage of the acetate groups of the EVA were converted into alcohol groups to form EVA-OH as follows:

Next, 1.0 N methanolic HCl solution was added to the solution to neutralize and stop the reaction. The reaction was performed at a temperature of 37.8° C. with a reaction time of 108 minutes. Following reaction, the final product was precipitated in methanol and dried under vacuum at 100° C. The final EVA-OFT terpolymer had a composition of 58% ethylene, 36% vinyl acetate, and 6% vinyl alcohol, confirmed by titration and NMR methods. ¹H NMR (400 MHz, CDCl₃): δ 3.5-4.0 (OH), 1.9-2.2 (CH₃), 1.4-1.9 (CH ₂—CH), 0.7-1.4 (CH ₂—CH ₂).

Cured EVA-OH

The cured EVA-OH polymer matrix was prepared by reacting hydroxyl groups on the vinyl alcohol monomers of the EVA-OH polymer with a phenol blocked diisocyanate to form a cross-linked polymer network. The phenol blocked diisocyanate, diphenyl-4,4′-methylene-bis(phenylcarbamate) (“DP-MDI”), was prepared by reacting phenol with methylene-bis(4-phenyl-isocyanatate) (“MDI”) in the presence of an amine catalyst (N,N,N′,N′-tetramethyl-1,3-butanediamine) at room temperature. A 2-L glass reactor was charged with 1,200 g of toluene, 2.8 g of N,N,N′,N′-tetramethyl-1,3-butanediamine (19.4 mmol), and 119.5 g of phenol (1.7 mol). The reactants were melted at 43.3° C. While vigorously stirring the resulting mixture, MDI (140.5 g, 0.56 mol) dissolved in toluene (61.1 g) was slowly dripped into the 2-L reaction vessel. The reaction was stirred for 1 hour, and the final product (a white powder) was filtered, washed with toluene, and dried under vacuum at 85° C. The DP-MDI curing agent was characterized by gel permeation chromatography (97.2% purity), differential scanning calorimetry (nadir melt peak=200.1° C.) and thermogravimetric analysis (96.3% step transition with onset at 231.2° C. end at 263.5° C. and at 275° C. wt % equal 4.9%), and ¹H NMR (400 MHz, THF-d₈): δ 9.10 (s, NH), 3.87 (s, CH ₂), 7.0-7.5 (aromatic protons).

Example 2 Synthesis of Boron Cage Compounds (“BCC”)

Four different boron cage compounds were prepared to be combined in various fashion with the above-described polymer matrices. The boron cage compounds included: n-hexyl carborane, 1,3-di-o-carboranylpropane (“tethered carborane”), 1,2-bis-(hydroxymethyl)-o-carborane (“carborane diol”), and dilithium dodecahydrododecaborate (Li₂ ²⁺[B₁₂H₁₂]²⁻). Note that the terms “carborane” and “o-carborane” as used in the Examples described herein, are intended to denote 1,2-closo-dicarbadodecaborane (C₂B₁₀H₁₂). As used elsewhere, such as the Detailed Description and the Claims included herein, the term “carborane,” as defined above, shall denote a chemical compound consisting of boron, hydrogen, and carbon atoms, exclusive of any pendant group atoms.

n-Hexyl Carborane

The n-hexyl carborane was prepared as follows. 105 g of decaborane (1.7 mol) was dissolved in 4 L of toluene in a 12-L reaction vessel equipped with a magnetic stir bar and heating mantle. 1 L of acetonitrile was added slowly using an addition funnel. A water condenser was placed in the reaction vessel and the mixture was heated at reflux overnight. 187.3 g of 1-octyne (1.7 mol) was dissolved in 2 L of toluene and this solution was added slowly to the stirring reaction at room temperature. The reaction was when refluxed for three days and then allowed to cool to room temperature. Solvent was removed in vacuo to give a dark brown oil, which was extracted with ether and washed with water. The ether was removed in vacuo and the resulting oil was dissolved in dichloromethane (1 L). The solution was washed three times with 100 mL of concentrated sulfuric acid, followed by five, 500 mL volumes of 1:1 water/saturated brine. The resulting tan-colored organic layer was dried over anhydrous magnesium sulfate, which was removed by filtration. The solvent was removed in vacuo to produce a rose-colored, viscous oil (221 g, 56.9% crude yield). Purification of the desired product was achieved through vacuum distillation using a high vacuum line equipped with a diffusion pump. The impure product was heated using an oil bath and product distilled with an oil temperature of 135° C. The clear, colorless, and viscous product was collected (198 g, 51% yield; density: 0.88 g/mL) and analyzed.

The resulting purified n-hexyl carborane had the following properties: ¹H NMR (500 MHz, CD₂Cl₂): δ 3.67 (s, 1H, cage C—H), 2.21 (t, 3H, —CH₃), 1.45 (m, 2H, —CH₂—), 1.24 (m, 6H, —CH₂—), 0.82 (t, 3H, —CH₂—). Note that the B—H protons are not resolved, which are typically and characteristically observed as a broad band between 2.90 and 1.60 ppm. ¹³C{¹H} NMR (125 MHz, CD₂Cl₂): δ 75.82 (BC), 61.22 (BC—H), 37.92, 31.44, 29.08, 28.45, 22.37, 13.63, (CH₂CH₂CH₂CH₂CH₂CH₃). ¹¹B{¹H} NMR (160 MHz, CD₂Cl₂): δ 2.71 (1B), −6.16 (1B), −9.57 (2B), −11.42 (2B), −12.16 (2B), −13.22 (2B). Mass spectroscopy (APCI, M⁻, 100%, m/z): calculated for C₈H₂₄B₁₀, 228.11; found, 228.11.

Tethered Carborane

A solution of 1,3-bis(silyl-o-carboranyl) propane (2.5 g, 4.5 mmol) in a dry tetrahydrofuran (“THF”) was cooled to −76° C. and 1.0 M solution of tetrabutylammonium fluoride in THF (9.2 mL, 9.2 mmol) was added dropwise with stirring. The mixture was allowed to stir for 30 minutes while being warmed to room temperature, and then 20 mL of water was added. The solution was diluted with 100 mL of diethyl ether and transferred to a separatory funnel. The layers were separated and the aqueous layer was extracted with additional diethyl ether (2×100 mL). The combined extracts were dried over anhydrous magnesium sulfate and concentrated in vacuo. The tethered carborane product was isolated as a white solid in 77.3% yield (1.14 g, 3.48 mmol) by column chromatography (flash silica gel) using hexane:ethyl acrylate, 3:1 as the eluent.

The resulting tethered carborane had the following properties: mass spectroscopy (APCI, M⁻, 100%, m/z): calculated for C₇H₂₈B₂₀, 328.52; found, 328.4. ¹H NMR (500 MHz, CD₂Cl₂): δ 1.652-1.756, 2.132-2.255, and 3.500-3.643 ppm. ¹³C{¹H} NMR (125 MHz, CDCl₃): δ 73.59, 61.27, 36.82, 28.64 ppm.

Carborane Diol

75 g of decaborane (1.2 mol) was dissolved in 2 L of toluene in a 5-L reaction vessel equipped with a magnetic stir bar and heating mantle. 500 mL of acetonitrile was added slowly using an addition funnel. A water condenser was placed on the reaction vessel and the mixture was heated at reflux overnight. 204.2 g of 1,4-diacetoxy-2-butyne (1.2 mol) was dissolved in toluene (500 mL and added slowly to the stirring reaction mixture at room temperature. The reaction was then refluxed for two days and allowed to cool to room temperature. The solvent was removed in vacuo. The obtained crude product, 1,2-bis-(acetoxymethyl)-carborane, was dissolved in 500 mL of dry methanol. This solution was heated to reflux and dry HCl gas was bubbled through the solution for 3 hours. The methanol and methyl acetate formed was removed by distillation leaving the crude product as white solid. 1,2-bis(hydroxymethyl)-carborane (a.k.a., carborane diol) was purified through two successive recrystallizations by dissolving it in hot toluene (200 mL) followed by filtration while hot. The filtrate was placed in a refrigerator and allowed to crystallize overnight. The product was filtered and washed with cold toluene and pentane (129.9 g, 53.1% yield).

The resulting purified carborane diol was analyzed and had the following properties: ¹H NMR (500 MHz, CD₃CO): δ 5.19 (t, 2H, —OH), 4.22 (d, 4H, —CH₂). Note that the B—H protons are not resolved, which are typically and characteristically observed as a broad band between 2.90 and 1.60 ppm. ¹³C{¹H} NMR (125 MHz, CDCl₃): δ 82.3 (BC), 64.5 (CH₃). ¹¹B{¹H} NMR (160.4 MHz, CD₂Cl₂): δ −2.95 (2B), −9.68 (2B), −10.26 (2B), −10.67 (48). Mass spectroscopy (APCI, M⁻, 100%, m/z): calculated for C₄H₁₆B₁₀, 206.208; found, 206.211.

Dilithium Dodecahydrododecaborate (Li₂[B₁₂H₁₂])

In preparing the dilithium dodecahydrododecaborate, lithium hydroxide and BIO RAD AG 50W-X8, 100-200 mesh ion exchange resin were purchased from Aldrich and Fisher Chemicals and used as received. Ion exchange resin (Bio Rad AG 50W-X8, 100-200 mesh) was used to convert K₂[B₁₂H₁₂] to Li₂[B₁₂H₁₂] as follows: in a 2,000-mL column, 800 mL of acid-form resin was washed with ion-free water until a pH of 7.0 was obtained. A solution of 5% lithium hydroxide was passed over the column until a pH of 12 was reached. The resin was wahed with ion-free water until a pH of 7.0 was reached, and then an aqueous solution of 50 g of K₂[B₁₂H₁₂] was passed through the column. The water was removed via rotary evaporator. The remaining trace of water was removed by lyophilization from the resulting white solid of dilithium dodecahydrododecaborate. Yield: 35.1 grams (99%). ¹¹B{¹H} NMR (160.4 MHz, H₂O): δ −15.4 (s, 12B).

Example 3 Preparation and Analysis of n-Hexyl Carborane/EVA Nanocomposites Dissolution Method

The following method was employed in preparing each of the nanocomposites described below. EVA or EVA-OH was dissolved in 200 mL of THF in a stirred Erlenmeyer flask. In a separate container, the boron cage compound was dissolved in THF and added to the flask. If the sample was to be cured, diphenyl-4,4′-methylene-bis(penylcarbamate) (“DP-MDI”) was also dissolved in THF and then added to the flask. Typically 9 parts by weight DP-MDI was added per 100 parts by weight EVA-OH. The entire solution was allowed to stir until homogenous. The solution was poured into a pan with a TEFLON® liner and allowed to air dry. Once the majority of the THF had evaporated and the sample was solid, the resulting film was then heated in a convection oven at 70° C. for three hours to remove any residual THF. The samples were then pressed into sheets at 100° C. in molds into 50.8 mm×50.8 mm squares nominally 3.2-3.3 mm thick. If it was a cured sample, the temperature was raised to 180° C. to react the DP-MDI with the EVA-OH and cross-link the elastomer. Cured samples were then post-cured at 130° C. in a convection oven for three hours to remove the phenol byproduct (unless otherwise stated).

Preparation of n-Hexyl Carborane/EVA Nanocomposites

Nanocomposite samples were prepared with n-hexyl carborane in EVA, EVA-OH, and cured EVA-OH matrix systems. Using the above-described dissolution method, 5%, 10%, and 25% n-hexyl carborane as prepared in Example 2 was incorporated into uncured EVA-OH. Into uncured EVA, 10% n-hexyl carborane was added (Sample ID NHC-6). For the cured EVA-OH system, 1%, 2%, 5%, 10%, 25%, and 50% n-hexyl carborane samples were prepared by this method. It should be noted that n-hexyl carborane is volatile, and care must be taken during the initial bake out to remove the THF and also the post-cure to remove the phenol to not evaporate the n-hexyl carborane out of the sample. To verify the n-hexyl carborane concentrations in the samples, the total boron contents of the samples were determined. The samples were digested by acids followed by analysis using Inductively Coupled Argon Plasma Spectrometry performed on a Thermo Elemental Iris Intrepid. The measured results compared to the initial contents are shown in Table 1, below. The EVA-OH uncured samples loaded with 5%, 10%, and 25% n-hexyl carborane (Sample IDs NHC-2, NHC-3, and NHC-4, respectively) were determined to have 5.3, %, 10.2%, and 26.4% n-hexyl carborane contents showing generally good agreement with the target compositions. Thus, the bake out procedure used to remove the THF (70° C. for 3 hours) does not seem detrimental to the composition for n-hexyl carborane samples. However, the cured EVA-OH sample sets require additional bake out process to remove phenol (post-cure). Samples were prepared with 1%, 2%, 5%, 10%, and 25% n-hexyl carborane in EVA-OH (Sample IDs NHC-8, NHC-9, NHC-10, NHC-11, and NHC-12, respectively), cured with DP-MDI at 180° C., and post cured at 130° C. for 3 hours. The cured samples were also tested for total boron content and shown in Table 1, which reveals that the higher temperatures did cause a decrease in the n-hexyl carborane content in the samples. This effect was especially evident at higher loadings. After bake out, the 25% sample had only 8.9% n-hexyl carborane left. Therefore, two additional samples of 25% n-hexyl carborane in cured EVA-OH (Sample IDs NHC-13 and NHC-14) were prepared and post-cured in a static oven at 160° C. and 130° C., respectively. The sample cured at 160° C. (NHC-13) was determined to have an n-hexyl carborane content of 15.2% and the sample post-cured at 130° C. (NHC-14) was found to have 21.6% remaining. A final sample was prepared with a target concentration of 50% n-hexyl carborane in cured EVA-OH (Sample ID NHC-15) and cured using the 130° C. static oven post-cure method. It was found to have 43.5% n-hexyl carborane remaining.

TABLE 1 n-Hexyl Carborane/EVA Nanocomposites Target Measured Post-Cure Sample ID Sample Description % BCC % BCC Method NHC-1 0% n-hexyl carborane - EVA-OH  0% — — uncured NHC-2 5% n-hexyl carborane - EVA-OH  5% 5.3% — uncured NHC-3 10% n-hexyl carborane - EVA-OH 10% 10.2% — uncured NHC-4 25% n-hexyl carborane - EVA-OH 25% 26.4% — uncured NHC-5 0% n-hexyl carborane - EVA  0% — — uncured NHC-6 10% n-hexyl carborane - EVA 10% — — uncured NHC-7 0% n-hexyl carborane - EVA  0% — 130° C. for 3 h in cured convection oven NHC-8 1% n-hexyl carborane - EVA-OH  1% 1.2% 130° C. for 3 h in cured convection oven NHC-9 2% n-hexyl carborane - EVA-OH  2% 1.3% 130° C. for 3 h in cured convection oven NHC-10 5% n-hexyl carborane - EVA-OH  5% 2.6% 130° C. for 3 h in cured convection oven NHC-11 10% n-hexyl carborane - EVA-OH 10% 4.7% 130° C. for 3 h in cured convection oven NHC-12 25% n-hexyl carborane - EVA-OH 25% 8.9% 130° C. for 3 h in cured convection oven NHC-13 25% n-hexyl carborane - EVA-OH 25% 15.2% 160° C. for 3 h in cured static oven NHC-14 25% n-hexyl carborane - EVA-OH 25% 21.6% 130° C. for 3 h in cured static oven NHC-15 50% n-hexyl carborane - EVA-OH 50% 43.5% 130° C. for 3 h in cured static oven Analysis of n-Hexyl Carborane Nanocomposites AR-G2 Rheology for Uncured n-Hexyl Carborane Samples

The storage modulus and loss modulus from the AR-G2 rheology test were plotted as a function of temperature of the above-described n-hexyl carborane nanocomposites prepared in uncured EVA-OH. Both storage and loss moduli decreased with increasing amounts of n-hexyl carborane. The transition region from a rubbery material to a glassy state (for these systems, begins at −15 to −35° C.), the n-hexyl carborane shifted this transition to lower temperatures pointing to lower glass transition temperatures (“Tg”). Typically, the peak maximum of a tan δ (G″/G′) as a function of temperature plot is identified as the Tg and for the n-hexyl carborane in uncured EVA-OH systems, which is plotted in FIG. 1. As can be seen in FIG. 1, the Tg shifts to the left (i.e., decreases) with increasing amounts of n-hexyl carborane. This trend indicates that the n-hexyl carborane acts as a plasticizing filler in the nanocomposite.

Uncured EVA with 10% n-hexyl carborane (Sample ID NHC-6) was evaluated to determine if there was any difference between the interaction with a different, modified polymer matrix (i.e., EVA versus EVA-OH). The tan δ plot as a function of temperature for uncured EVA samples is shown in FIG. 2. Again, the n-hexyl carborane decreased the Tg for uncured EVA. For EVA and EVA-OH there were actually two thermal transitions, which likely occurred because of the two different monomers present. The lower temperature transition could have been due to the polyethylene segments, and for the EVA-OH occurred at −21.6° C. and at −23.7° C. for EVA as shown in the tan δ plots of FIGS. 1 and 2, respectively. The other transition was likely primarily due to the vinyl acetate segments and occurred around 45° C. (not shown).

Melt Viscosity for Uncured n-Hexyl Carborane Nanocomposites

The above-described RPA2000 rheometer was used to obtain the melt viscosity of uncured EVA (Samples NHC-5 and -6) and EVA-OH (Samples NHC-1 to -4) n-hexyl carborane nanocomposites at elevated temperatures when the nanocomposite samples were completely melted. The melt viscosity was determined as a function of percent n-hexyl carborane for uncured EVA and EVA-OH. The melt viscosity was determined at 121° C. and correlates to the typical mold temperature for parts made from EVA or EVA-OH. Both EVA and EVA-OH showed a decrease in melt viscosity with increasing amounts of n-hexyl carborane.

AR-G2 Rheology for Cured n-Hexyl Carborane Samples

Cured and post-cured samples of n-hexyl carborane in EVA-OH (Sample IDs NHC-7 to -15) were tested by the AR-G2 rheology test. As observed with the uncured samples, the storage modulus decreased with increasing amounts of n-hexyl carborane. FIG. 3 shows the tan δ plots for the cured EVA-OH samples. Since these samples are cured, the temperature sweeps include higher temperatures and both thermal transitions are seen. Although the transition associated with the vinyl acetate monomers was a much smaller peak, both thermal transitions show a decrease with increasing amounts of n-hexyl carborane.

Glass Transition Temperatures for n-Hexyl Carborane Samples

The primary tan δ maximum peaks were plotted for the uncured EVA-OH (Samples NHC-1 to -4), uncured EVA (Samples NHC-5 and -6), and cured EVA-OH (Samples NHC-7 to -15) nanocomposite samples. That plot showed the glass transition temperatures for n-hexyl carborane samples decreased for all three polymer systems at about the same degree. All three had similar slopes and decreases in glass transitions. There was a slight difference in the initial Tg (starting point at 0% n-hexyl carborane) for the three polymer systems. The uncured EVA-OH has a slightly higher Tg (−21.6° C.) than the uncured EVA (−23.7° C.) and could possibly be explained by potential hydrogen bonding between hydroxyl groups, which limits the rotational freedom of the EVA-OH polymer chain. Further restriction of the rotational freedom of the EVA-OH occurs when the system is cured, and again the Tg was higher (−15.5° C.) for the cured EVA-OH. The smaller, secondary thermal transition (due to the vinyl acetate segments) was not plotted in a similar manner since the peak is smaller and more difficult to determine the peak position. The 43.5% n-hexyl carborane in cured EVA-OH (Sample NHC-15) clearly showed a decrease in the maximum for this secondary transition from the baseline sample (26.6° C. versus 32.2° C.), but the change was much smaller than that found for the primary transition. Finally, these results again show that n-hexyl carborane plasticizes uncured EVA-OH, uncured EVA, and cured EVA-OH polymer matrices.

Thermal Data for n-Hexyl Carborane Samples

DSC and TGA were used to further evaluate thermal behavior of Samples NHC-1 to -15. n-Hexyl carborane has a thermal transition at −92° C.; however, none of the DSC curves for the n-hexyl carborane nanocomposite samples exhibited a thermal transition in this region. The DSC data agreed with the rheology data showing lower glass transition temperatures and plasticization. The peak around 45° C. due to vinyl acetate segments did not appear to change even at high n-hexyl carborane contents. The addition of n-hexyl carborane did not improve the thermal stability of the samples upon analysis by TGA. Lower T₅, T₁₀, and T₂₅ temperatures were found with increasing amounts of n-hexyl carborane. It should be noted that T_(#) is a convention used to note the temperature at which a certain weight percent of a given sample, which is being tested by TGA, has been lost to volatilization. Thus, for example, T₅, T₁₀, and T₂₅ are the temperatures where 5 weight percent, 10 weight percent, and 25 weight percent of the initial sample weight has been volatilized, respectively.

Example 4 Preparation and Analysis of Tethered Carborane/EVA Nanocomposites Preparation of Tethered Carborane/EVA Nanocomposites

Using the dissolution method described in Example 3 above, 0%, 1%, 5%, 10%, and 25% tethered carborane as prepared in Example 2 was loaded into uncured EVA-OH (Sample IDs TC-1, TC-2, TC-3, TC-4, and TC-5 respectively). Additionally, 0% and 10% tethered carborane was incorporated into uncured EVA (Sample IDs TC-6 and TC-7). For the EVA-OH system, 0%, 5% and 10% tethered carborane samples (Sample IDs TC-8, TC-9, and TC-10) were prepared. The total boron contents were confirmed on select samples, and the volatility associated with n-hexyl carborane (described above) was not found for tethered carborane. In the uncured EVA-OH tethered carborane nanocomposites, the samples prepared containing up to 10% tethered carborane remained clear. However, at 25% tethered carborane, the resulting sample was opaque and white in color. This indicates that the solubility of the tethered carborane reaches a saturation point somewhere between 10% and 25%, and some tethered carborane had phase separated out.

AR-G2 Rheology for Uncured Tethered Carborane Samples

The storage and loss moduli were determined by AR-G2 rheology test for the tethered carborane in uncured EVA-OH nanocomposites (Sample IDs TC-1 to TC-5). The storage and loss moduli increased or decreased depending on the amount of tethered carborane present and the temperature region. From −10° C. to 30° C., the 1%, 5%, and 10% tethered carborane nanocomposites (Samples TC-2, TC-3, and TC-4) showed lower storage and loss modulus values than the baseline uncured EVA-OH (Sample TC-1). Conversely, the 25% tethered carborane nanocomposite (Sample TC-5) had higher modulus values over this same temperature region. The tethered carborane shifted the transition from rubbery to glassy state to higher temperatures. Thus, at lower temperatures (−15 to −35° C.), the storage and loss modulus values were higher with increasing tethered carborane contents.

FIG. 4 shows the tan δ plots of tethered carborane in uncured EVA-OH. The Tg increased up to 10% tethered carborane, after which additional tethered carborane had no further effect on the tan δ peak maximum temperature. This result parallels the solubility of the tethered carborane. It was noted earlier that tethered carborane is soluble up to 10% in EVA-OH and at 25% tethered carborane the system is saturated and an opaque sample was observed. Likewise, the tethered carborane only affected the glass transition temperature up to 10%, after which no further changes were found. In uncured EVA, 10% tethered carborane increased the glass transition temperature at about the same level to what was observed in the uncured EVA-OH system.

Melt Viscosity for Uncured Tethered Carborane Samples

The melt viscosities as a function of tethered carborane content for uncured EVA (Samples TC-6 and TC-7) and EVA-OH (Samples TC-1 to -5) were plotted. These plots reflected the trends observed in the storage and loss modulus data from the AR-G2 test. Up to 10% tethered carborane, softer samples were found, and, likewise, lower melt viscosities were found from 1 to 10% tethered carborane. The melt viscosity then went back up with 25% tethered carborane (again, similar to the storage and loss modulus). It was not clear why the storage and loss moduli increased between 10% and 25%. Though not wishing to be bound by theory, one possible explanation is that the insoluble tethered carborane in the system was behaving like a normal, traditional filler. The insoluble tethered carborane present in this sample may have caused macroscopic filler reinforcement resulting in higher melt viscosities and higher storage and loss moduli, but it may have had no further effect the glass transition temperature.

AR-G2 Rheology Data for Cured Tethered Carborane Samples

Cured and post-cured samples of tethered carborane in EVA-OH were tested by the AR-G2 rheology test. The primary tan δ peak increased and the smaller secondary peak slightly decreased with increasing tethered carborane contents in the cured EVA-OH system.

Glass Transition Temperatures for Tethered Carborane Samples

The primary tan δ peaks for the uncured EVA-OH (Samples TC-1 to -5), uncured EVA (Samples TC-6 and -7), and cured EVA-OH (Samples TC-8 to -10) were plotted as a function of tethered carborane and compared. These plots showed the glass transition temperatures for tethered carborane samples increased for all three polymer systems up to 10% tethered carborane, after which it plateaued for the uncured EVA-OH samples with higher loading. In addition, all three polymer systems had similar slopes (at least up to 10%). While the increase in glass transition temperatures is normally indicative of reinforcement by the tethered carborane, this result is countered by the observed lower storage modulus, lower loss modulus, and decreased melt viscosity, which are normally observed with plasticized systems. Thus, depending on the temperature region and definition used, the tethered carborane both reinforced and plasticized EVA and EVA-OH.

Thermal Data for Tethered Carborane Samples

DSC curves for the first heat cycle of tethered carborane samples in uncured EVA-OH were prepared. The onset for the 5%, 10%, and 25% tethered carborane (Samples TC-3, TC-4, and TC-5, respectively) were clearly increased over the baseline EVA-OH. It appears that TC-4 and TC-5 had similar shifts in onset reflecting what was observed in the AR-G2 rheology data. The vinyl acetate peaks at 45° C. appear unchanged with the presence of tethered carborane. The 25% tethered carborane in EVA-OH sample (TC-5) had an additional peak at 94.1° C. which is consistent with the melting point of tethered carborane at 92.4° C. This result confirmed the visual inspection of the sample, which was opaque/white, indicating some level of insolubility was present. Once the saturation point had been reached, the sample showed a melting peak due to tethered carborane phase separation. The TGA data showed that the tethered carborane did not improve the thermal stability of the samples. Lower T₅, T₁₀, and T₂₅ temperatures were found with increasing amounts of tethered carborane, although the effect was less pronounced than observed with the n-hexyl carborane samples described above.

Example 5 Preparation and Analysis of Carborane Dial/EVA Nanocomposites Preparation of Carborane Diol/EVA Nanocomposites

Using the dissolution method described in Example 3 above, 0%, 1%, 5%, 10%, and 25% carborane diol as prepared in Example 2 was incorporated into uncured EVA-Oil (Sample IDs CD-1, CD-2, CD-3, CD-4, and CD-5, respectively), and 0% and 10% of carborane diol was incorporated into uncured EVA (Sample IDs CD-6 and CD-7). Visual inspection of the carborane diol samples revealed clear samples with no opacity up to the 25% loadings indicating that the carborane diol is miscible with EVA-OH and EVA at these levels. Carborane diol is a white solid with a melt temperature of 79.6° C.

AR-G2 Rheology for Uncured Carborane Diol Samples

The storage and loss moduli from the AR-G2 rheology test were plotted for carborane diol in uncured EVA-OH. As found with the tethered carborane system, the storage and loss moduli increased or decreased depending on the amount of carborane diol present and the temperature region. From room temperature to the Tg temperature region, the samples with carborane diol were softer as demonstrated by lower storage and loss moduli than the baseline uncured EVA-OH sample. The carborane diol samples also displayed a small shift in the glass transition temperature with increasing carborane diol contents; however, this effect was much smaller than observed with the tethered carborane. This shift was more easily seen in the tan δ plot (FIG. 5). As seen in FIG. 5, peak maximums in the tan δ plots stay about the same or shift slightly to the right with increasing carborane diol contents. Without vinyl alcohol segments, incorporation into EVA had even less of an effect on the Tg when 10% carborane diol is introduced.

Melt Viscosity for Uncured Carborane Diol Samples

The melt viscosity of the carborane diol in uncured EVA-OH and EVA was determined. The results of the melt viscosity determination reflected the trends observed in the storage and loss modulus data from the AR-G2 test; the melt viscosity consistently decreased with increasing carborane dial contents.

Glass Transition Temperatures for Uncured Carborane Diol Samples

The primary tan δ maximum for the uncured EVA-OH and uncured EVA were plotted and compared as a function of carborane diol. The carborane diol showed no change in the glass transition temperature in uncured EVA and exhibited a slight increase in uncured EVA-OH. These shifts in glass transition temperatures for carborane diol in uncured EVA-OH were less than observed for the tethered carborane. This result is surprising since the carborane diol has the potential of additional interaction from hydrogen bonding with the vinyl alcohol segments of the EVA-OH. The carborane diol was more soluble than the tethered carborane, illustrated by clear, soluble samples up to 25%, whereas the 25% tethered carborane sample was opaque and has some phase separation. While solubility would seem to be a prerequisite to be a “good” nanofiller, soluble boron cage compounds are not always reinforcing as evidenced by the highly soluble n-hexyl carborane. In carborane diol samples, no change or a small increase in Tg indicates some reinforcement; however, like the tethered carborane system, lower storage moduli, loss moduli, and melt viscosities were found, which indicates plasticization. Hence, the carborane diol system demonstrated evidence of both reinforcement and plasticization depending on the conditions.

Thermal Data for Carborane Diol Samples

Thermal data from DSC analysis for the carborane diol samples support the AR-G2 rheology results. None of the carborane dial nanocomposite samples had a peak around 80° C., which is the melting point of carborane diol. This is not surprising since all of the carborane diol samples appeared soluble in EVA and EVA-OH. The thermal stability was reduced with carborane diol present and showed lower T₅, T₁₀, and T₂₅ temperatures with increasing amounts of carborane diol.

Example 6 Preparation and Analysis of Li₂[B₁₂H₁₂]/EVA Nanocomposites Preparation of Li₂[B₁₂H₁₂]/EVA Nanocomposites

Using the dissolution method described in Example 3 above, 0%, 1%, 2%, 5%, 10%, and 25% Li₂[B₁₂H₁₂] as prepared in Example 2 was incorporated into uncured EVA-OH (Sample IDs LBH-1, LBH-2, LBH-3, LBH-4, LBH-5, and LBH-6, respectively). Additionally, 0% and 10% of Li₂[B₁₂H₁₂] was incorporated into uncured EVA (Sample IDs LBH-7 and LBH-8, respectively). For the cured EVA-OH system, 0%, 5%, 10%, and 25% samples were prepared using the same method (Sample IDs LBH-9, LBH-10, LBH-11, and LBH-12, respectively). During sample preparation, Li₂[B₁₂H₁₂] was observed to rapidly absorb moisture out of the air. Initial samples were weighed on a scale in air and the measured weights increased considerably over time. Subsequent Li₂[B₁₂H₁₂] samples were weighed on a scale inside a glove box with low moisture levels. Some samples were dried further under vacuum at 100° C. overnight, while others were tested immediately. Additional corresponding samples that underwent vacuum drying are designated with a “V” following the Sample ID, and included LBH-1V, LBH-2V, LBH-3V, LBH-4V, LBH-5F, LBH-6V, LBH-9V, and LBH-10V. Samples were stored in a desiccated environment.

Li₂[B₁₂H₁₂], is a white solid with a melting temperature of 131.1° C. In uncured EVA-OH, Li₂[B₁₂H₁₂] samples were less clear than other soluble BCC samples, almost translucent. Up to 10% Li₂[B₁₂H₁₂], the samples were translucent in color and at higher loadings (25%) were white and completely opaque. This effect would indicate some level of insolubility of Li₂[B₁₂H₁₂] at higher loadings as found in the tethered carborane system. Initially, 5%, 10%, and 25% Li₂[B₁₂H₁₂] was incorporated into EVA-OH and cured with DP-MDI. These samples had issues with incomplete curing and non-uniformity (bubbles). The source of the incomplete cure and bubbles was likely due to the moisture affinity of the Li₂[B₁₂H₁₂]. The moisture can react with the DP-MDI curing agent releasing phenol, limiting the reaction with EVA-OH, and lowering the crosslink density. The 10% Li₂[B₁₂H₁₂] cured sample was repeated after drying the material under vacuum at 100° C. This sample was improved and appeared to be more cured, but still had a few bubbles present. It was very difficult to eliminate all of the moisture present in the Li₂[B₁₂H₁₂].

AR-G2 Rheology Data for Uncured Li₂[B₁₂H₁₂] Samples

In the three BCC systems discussed above, the BCCs have either decreased glass transition temperatures (plasticization with n-hexyl carborane) or only slightly increased the glass transition temperatures (tethered carborane and carborane diol), but generally “softer” materials were found at higher temperatures. Large shifts in Tg, increased mechanical strength, and increased thermal stability are often found in polymers reinforced with a nanofiller. Finally, the case of a boron cage compound reinforcing a polymer will be presented in the Li₂[B₁₂H₁₂] system.

Samples of Li₂[B₁₂H₁₂] in uncured EVA-OH were dried under vacuum at 100° C. and tested immediately by the AR-G2 rheology test. From this analysis, the storage modulus plots are shown in FIG. 6 and loss modulus plots in FIG. 7. In these two plots, the increase in storage and loss modulus upon incorporation of Li₂[B₁₂H₁₂] is clearly seen and is substantial. The Li₂[B₁₂H₁₂] samples were much stiffer, even allowing higher initial temperatures to be used during the rheology test. Even though they are uncured, the reinforced Li₂[B₁₂H₁₂] samples did not deform under the 5 N of force applied during testing. It should be noted that the Li₂[B₁₂H₁₂] samples prepared by the normal procedure (not vacuum dried) also exhibited large increases in storage and loss modulus.

The tan δ plots of Li₂[B₁₂H₁₂] in uncured EVA-OH (vacuum dried) are shown in FIG. 8. The glass transition temperatures for these samples increased dramatically (shifting to the right) with increasing Li₂[B₁₂H₁₂] contents. However, it is difficult to pick the exact position of the glass transition temperature for these plots. The 25% Li₂[B₁₂H₁₂] sample (LBH-6) has a fairly broad tan δ peak with a main peak around 91° C. and a shoulder around 75° C. EVA-OH and EVA have two transitions, one due to polyethylene and the other to vinyl acetate segments. With LBH-6, it appears the two peaks were overlapping, making it impossible to determine which was which by this analysis alone. It also looks as if the Li₂[B₁₂H₁₂] reinforced both types of segments, as both Tgs were higher than the baseline EVA-OH. The Li₂[B₁₂H₁₂] also impacted uncured EVA in a similar fashion: increased storage modulus, increased loss modulus, and increased glass transition temperature.

Melt Viscosity Data for Uncured Li₂[B₁₂H₁₂] Samples

The melt viscosity as a function of Li₂[B₁₂H₁₂] content was plotted for uncured EVA and EVA-OH. These samples were not dried further under vacuum, but were tested immediately after the 70° C. per 3 hour bake out. In EVA-OH, the melt viscosity increased up to 10% Li₂[B₁₂H₁₂] (LBH-5) and then plateaued with only a small increase observed in the 25% sample (LBH-6) over the 10% sample (LBH-5). The uncured EVA sample (LBH-8) had a slightly lower melt viscosity verses its EVA-OH counterpart (LBH-5); however, it still increased substantially. FIG. 9 demonstrates how the melt viscosities of the Li₂[B₁₂H₁₂] samples in uncured EVA-OH compared to the other boron cage compounds in uncured EVA-OH, described in Examples 3, 4, and 5, above. As can be seen in FIG. 9, the other BCCs decreased the melt viscosity of the nanocomposite while the Li₂[B₁₂H₁₂] increased it and reinforced the polymer matrix, even when melted.

Glass Transition Temperatures for Li₂[B₁₂H₁₂] Samples

The peak maximums from Li₂[B₁₂H₁₂] tan δ plots were plotted and compared for uncured EVA (Samples LBH-7 and -8), uncured EVA-OH (Samples LBH-1 to -6), vacuum dried uncured EVA-OH (Samples LBH-1V to -6V), and vacuum dried cured EVA-OH (Samples LBH-9V and -10V) systems. The curves for the uncured EVA and EVA-OH samples (not vacuum dried) resembled the trends from the melt viscosity test. Again, the Tg increased up to 10% and then plateaued and only slightly increased when the content was increased to 25% for the uncured EVA-OH samples. The Tg from the uncured EVA sample increased, but was slightly lower than its uncured EVA-OH equivalent. The 10% Li₂[B₁₂H₁₂] in cured EVA-OH sample that was dried further under vacuum had two peaks approximately the same size: one at 34.5° C. and the other at 73.5° C. The more conservative 34.5° C. was plotted and showed an increase in Tg with a similar slope as the other Li₂[B₁₂H₁₂] plots. Uncured EVA-OH samples that were vacuum dried continued to show an increase in Tg with addition of Li₂[B₁₂H₁₂]. This sample set did not show the plateau between 10 and 25% Li₂[B₁₂H₁₂] as observed with data for samples not vacuum dried (melt viscosity and Tg). It also looks as if the vacuum drying had the biggest impact on the 25% Li₂[B₁₂H₁₂] sample. The extraordinary properties made possible by incorporation of BCC nanofillers are highlighted by the 102.5° C. increase in glass transition temperature found in this sample.

FIG. 10 plots the peak maximum from tan δ as a function of percent boron cage compound for the BCCs evaluated, n-hexyl carborane, tethered carborane, carborane diol, and Li₂[B₁₂H₁₂]. This plot shows that the glass transition decreased with n-hexyl carborane, remained relatively unchanged with tethered carborane and carborane diol, and increased with Li₂[B₁₂H₁₂].

FIG. 11 illustrates how big of an impact the Li₂[B₁₂H₁₂] had on the glass transition temperature. It is difficult to determine the exact peak positions of the Li₂[B₁₂H₁₂] from the tan δ plots due to the formation of multiple and overlapping peaks. Another option to evaluate the glass transition temperature is to use the maximum of the loss modulus trace as the glass transition temperature. It should be noted that the maximum in the tan δ plot is always at a higher temperature than the maximum of the G″ trace. This is because the tan δ is the ratio of loss (G″) to storage (G′) moduli, and both are changing in the transition region. However, the peaks from the loss modulus plots are shown for all of the boron cage compounds in FIG. 11 to support the data in FIG. 10. Both FIGS. 10 and 11 have similar trends for the each of the corresponding four boron cage compounds, but the increase in glass transition temperature for Li₂[B₁₂H₁₂] samples are slightly greater when based on the tan δ plots than when determined by the loss modulus peak maximum. Regardless, the data consistently pointed to large increases in glass transition temperature and reinforcement of EVA-OH by Li₂[B₁₂H₁₂].

Thermal Data for Li₂[B₁₂H₁₂] Samples

Differential scanning calorimetry was used to further evaluate thermal behavior of Li₂[B₁₂H₁₂]. The 10% and 25% Li₂[B₁₂H₁₂] samples in uncured EVA-OH (not vacuum dried; LBH-5 and -6, respectively) exhibited large increases in the onset temperature over the baseline EVA-OH. Surprisingly, the vinyl acetate peaks for these DSC curves appeared unchanged even though a large change in mechanical properties was observed above this temperature. Like the 25% tethered carborane sample discussed above, which was also white indicating some level of insolubility, the 25% Li₂[B₁₂H₁₂] sample (LBH-6) showed a peak in the same position as the melting point of the Li₂[B₁₂H₁₂] around 131° C. The DSC curves for the vacuum dried samples (LBH-5V and -6V) showed some differences from those that did not have the additional drying. The onset temperatures were shifted to even higher temperatures, which was most noticeable with the vacuum dried 25% Li₂[B₁₂H₁₂] sample (LBH-6V). The Li₂[B₁₂H₁₂] melting peak around 131° C. was not found for this sample; however, it may have been simply masked by the other transition that was overlapping in that temperature region.

Thermogravimetric analysis (“TGA”) was used to evaluate the thermal stability of these nanocomposites. Decomposition curves for Li₂[B₁₂H₁₂], uncured EVA-OH (Sample LBH-1V), and Li₂[B₁₂H₁₂] nanocomposite samples in uncured EVA-OH (vacuum dried) (Samples LBH-2V to -6V) were prepared. The 100% Li₂[B₁₂H₁₂] TGA curve showed approximately 20 weight percent degradation around 100° C. and, although not confirmed, was most likely due to moisture absorbed by the Li₂[B₁₂H₁₂]. There is a second degradation from 190 to 250° C. which caused another 26 weight percent to be lost. At higher temperatures, the Li₂[B₁₂H₁₂] material was very thermally stable and did not exhibit additional degradation.

EVA-OH had two main thermal degradations. The first occurred at 315° C. and was known to be due to thermal scission of the acetate group, resulting in acetic acid evolution. A second degradation occurred at 420° C. and can be ascribed to the degradation of the resulting hydrocarbon backbone left behind.

For the Li₂[B₁₂H₁₂] nanocomposite samples, the presence of Li₂[B₁₂H₁₂] initially decreased the thermal stability, and lower T₅ temperatures were found. These lower initial thermal stabilities may have been due to the two degradations observed for the 100% Li₂[B₁₂H₁₂] sample. However, the degradations for the Li₂[B₁₂H₁₂] nanocomposites occurred at higher temperatures and had shapes and degradation temperatures that were more like the virgin uncured EVA-OH decomposition profile. Only in the decomposition profile of the 25% Li₂[B₁₂H₁₂] sample does this seem likely. Another possibility is that the Li₂[B₁₂H₁₂] promoted the loss of acetic acid. Costache et al. (2005) and Lee et al. (2007) reported a similar trend for EVA-clay nanocomposites. In EVA, the loss of acetic acid in the first degradation was catalyzed by the presence of the nanoclay. In EVA/clay nanocomposites, the remaining polymer backbone had additional thermal stability. Costache et al. postulated that when multiple degradation pathways were present, one pathway can be promoted at the expense of the other when clay is present. Similarly, for the Li₂[B₁₂H₁₂] system, the thermal stabilities were enhanced with increasing Li₂[B₁₂H₁₂] contents at higher temperatures. The T₁₀ temperatures for the 1%, 2%, 5%, and 10% Li₂[B₁₂H₁₂] samples were only slightly lower than the EVA-OH baseline material, and the 25% sample has a higher T₁₀ temperature. The T₁₀ temperature appears to be the changeover point of improved thermal stability of EVA-OH by Li₂[B₁₂H₁₂]. The T₂₅ temperatures for all of the Li₂[B₁₂H₁₂] samples were higher than the baseline material. This trend continued at higher degradations and higher temperatures.

Nanocomposites in Epoxy Polymers and Polyurethane Matrices Examples 7-13 Test Procedures for Examples 7-13

In the following Examples 7-13, nanocomposite test samples were subject to various characterization testing. The following procedures were employed.

AR-G2 Rheology

Rheology testing for Examples 7-13 was performed on a TA Aries 2000 or AR-G2 rheometer under torsion between 25 mm parallel plates. As much as possible, disks (diameter ˜11 mm, by ˜3.6 mm) of uniform size were used as samples. Samples that were thicker than ˜3.6 mm were sanded with an ultra-fine grit sand paper. All samples were subjected to a temperature sweep from low to high temperatures at strains of 0.1% or 0.05% and a frequency of 1 Hz. All experiments were performed under normal force control at 5.0 N, with a 0.5-N tolerance (gap=+/−500,000 nm). The temperature range varied depending on the locations of the expected transitions, but a 5-20 minute equilibration time was used once a sample reached the minimum temperature. A temperature ramp rate of 3° C./minute was used.

Differential Scanning Calorimetry (“DSC”)

Differential Scanning calorimetry was performed using a TA Q2000 instrument. All experiments were carried out on samples weighing between ˜8 mg and ˜18 mg using aluminum pans, using an identical, yet empty pan as a reference over the desired temperature range.

Thermogravimetric Analysis (“TGA”)

Thermogravimetric analysis was performed on clean Pt pans using a TA Q1000 instrument. Some carborane samples were tested using clean ceramic pans. All experiments were performed using a ramp rate of 10° C./minute over the desired temperature range. All experiments where performed under nitrogen. Samples that contained carborane all exhibited significant amounts of a voluminous and porous black ash, which could not be cleaned away by burning in a high temperature muffle furnace. Many of these samples had more weight, as a percentage of their starting weight, than could be accounted for in just boron.

Dynamic Mechanical Analyzer (“DMA”)

Dynamic Mechanical Analyzer analysis was performed using a TA Q800 instrument. Experiments were performed on disks of uniform size (diameter ˜11 mm, by ˜3.6 mm) at a set temperature of 0° C. Tests were performed on the disks in compression mode using controlled force. Four cycles where measured for each sample. Each cycle consisted of compressing the sample to 18 N, followed by releasing the sample to 0.1N, both at a rate of 3 N/minute.

Shore A Hardness

The Shore A hardness of samples was measured using an Instron Shore A Hardness tester, model 902 (Automatic Operating Stand). Between 3 and 5 (or more) separate measurements were taken on each sample. For very soft samples, for which the Shore A Hardness value continuously dropped, no value was recorded.

SEM Imaging

Microscopic images were taken using an LEO1455 VP Scanning Electron Microscope at 25 and 30 Kv energies in the variable pressure mode, which allows imaging of insulator materials without requiring the application of a conductive coating on the surface. The backscattered imaging detector was used to provide visual details of surface features and element differences that may be present in the material.

Example 7 Epoxy Polymers and Polyurethane Matrices

Epoxies, Etc. Epoxy

A commercially available epoxy polymer supplied by Epoxies, Etc., was employed as a polymer matrix in various examples below. This epoxy is an optically clear, two part material comprising a resin with an epoxy equivalent weight (“EEW”) of 230. The resin is >80 weight percent bisphenol A diglycidyl ether (“BADGE”), ˜2.5 to 10 weight percent 4-nonylphenol (branched), <10 weight percent bis(1,2,2,6,6-pentamethyl-4-piparidinyl) sebacate, and a small amount (<2 weight percent) xylene. The curative employed with this epoxy was an amine-terminated polyether based on polypropylene oxide, similar to Jeffamine D-230 or D-400 produced by Huntsman Performance Products.

Model Epoxy

The model epoxy formulation, which was clear, but slightly colored, comprised a resin based on EPON 828 (available from Hexion Specialty Chemicals, Inc.; EEW 185-192). EPON 828 is a low molecular weight epoxide resin of BADGE. The curative employed with this epoxy was EPIKURE 3270 (available from Hexion Specialty Chemicals, Inc.), which is a modified aliphatic amine, comprising primarily 4-nonylphenol, some 1-amionethyl piperazine, and small amounts of diethylenetriamine (“DETA”) or triethylenetetramine (“TETA”).

EN8 Urethane

EN8 is a two part polyurethane, comprising part A and part B, which is clear and orange-colored. The orange color is caused by the Fe(III)(acetylacetonate)₃ catalyst, which is present at the ppm level. Part A contains ˜88-90 weight percent of a toluenediisocyanate (“TDI”) end-capped polybutadiene and ˜10-12 weight percent TDI. Part B is 50 weight percent bis-(2-hydroxypropyl) aniline (“BHPA”), 50 weight percent 2-ethyl-1,3-hexane dial (“EHD”), and the catalyst.

Example 8 Synthesis of Boron Cage Compounds

Three different boron cage compounds were prepared to be combined in various fashion with the above-described epoxy or urethane polymer matrices. The boron cage compounds included: n-hexyl carborane, [(1,2-dicarba-closo-dodecaboran-1(2)-1-yl)methyl]-oxirane (“carborane epoxy”), and 1,2-bis-(hydroxymethyl)-o-carborane (“carborane diol”).

n-Hexyl Carborane

n-Hexyl carborane was prepared as described above in Example 2.

Carborane Diol

Carborane Diol was prepared as described above in Example 2.

Carborane Epoxy

Silyl-o-carborane, 3-(silyl-o-carboranyl)-1-propene, 3-o-carboranyl-1-propene, and CF₃CO₃H were prepared by procedures known in the art. n-Butyllithium (2.5 M solution in hexane), tetrabutylammonium fluoride, tert-butyldimethylchlorosilane (“TBDMS”), allyl bromide, trifluoroacetic anhydride, H₂O₂, and epichlorohydrin were purchased from Aldrich and Fisher chemicals, and each was used as received. Experiments were performed under an argon atmosphere in a Vacuum Atmospheres Corporation (VAC) dry box or on a Schlenk line with dried and de-aerated solvents. NMR spectra were recorded on Bruker AMX 250, 300, and 500 spectrometers at ambient probe temperatures. Shifts are given in parts per million (“ppm”) with positive values to higher frequency of TMS (¹H and ¹³C), external BF₃.OEt₂ (¹¹B). ¹¹B NMR spectra were recorded in proton-decoupled mode. Assignments were based on DEPT experiment and comparisons to similar complexes. Two different methods were employed for preparing the carborane epoxy: Method A and Method B.

In Method A, a solution of 3-o-carboranyl-1-propene (500 mg, 2.71 mmol) in CH₂Cl₂ (10 mL) was added at 0° C. to a stirred solution of peroxytrifluoroacetic acid (4.23 mg, 3.26 mmol). The mixture was continuously stirred for 24 h and then filtered via cannula. A yellow liquid was obtained by removal of solvent under reduced pressure. Chromatography on silica (50% ethyl acetate/hexane) afforded carborane epoxy (400 mg, 74% yield).

In Method B, to a solution of 1,2-dicarba-closo-dodecaborane (2.0 g, 13.8 mmol) in THF (30 mL) at 0° C. was added drop wise with stirring to a 2.5 M solution of n-butyllithium in hexane (6.10 mL, 15.2 mmol). The mixture was allowed to stir for 30 minutes while being warmed to ambient temperature. The solution was cooled to −76° C. and epichlorohydrin (1.30 mL, 16.6 mmol) in THF (10 mL) was added drop wise. Stirring was continued for 24 hours, over which time the colorless solution became yellow. The resulting solution was quenched with 60 mL of H₂O and transferred to a separatory funnel and diluted with 100 mL of CH₂Cl₂/OEt₂. The resulting layers were separated, and the aqueous layer was extracted with additional CH₂Cl₂ (2×30 mL). The combined extracts were concentrated in vacuo. Chromatography on silica (50% ethylacetate/hexane) afforded carborane epoxy as a white solid (2.4 g, 87% yield).

Analysis of the carborane epoxy yielded the following: ¹H NMR (500 MHz, CD₂Cl₂): δ 3.89 (s, CH, 1H), 3.08 (m, C—CH₂CHCH₂O, 1H), 2.876-2.45 (m, C—CH ₂CHCH₂O, 2H), 2.68-2.13 (m, C—CH₂CHCH ₂O, 2H), 2.72-1.72 (m, 10H). ¹³C{¹H} NMR (125.7 MHz, CD₂Cl₂): δ 72.9 (CH), 60.9 (C—CH₂CHCH₂O), 50.0 (C—CH₂ CHCH₂O), 46.9 (C—CH₂CHCH₂O), 41.5 (C—CH₂CHCH₂O). ¹¹B{¹H} NMR (160.4 MHz, CD₂Cl₂): δ −2.26 (d, J=149.2 Hz, 1B), −5.58 (d, J=149.2 Hz, 1B), −9.45 (d, J=149.2 Hz, 2B), −11.27 (d, 3B), −12.84 (d, J=174.9 Hz, 3B).

The carboranes used to make the nanocomposites described herein were stored under nitrogen in a −40° C. freezer contained within an inert atmosphere glove box while not in use. The n-hexyl carborane and carborane diol made herein remained at high purity. However, by TGA, the carborane epoxy appeared to degrade. The epoxy equivalent weight confirms that the carborane epoxy material degraded (EEW ca. 200.277; found 230) and was not more than ˜87 percent pure. Degradation occurred sometime after it was made and characterized, although there was no change in the material's physical appearance. Composites containing carborane epoxy (described below) were made prior to knowing that the material had degraded.

The TGA analyses of n-hexyl carborane and carborane diol were indicative of a volatilized, not decomposed or degraded, material. In contrast, the carborane epoxy and its decomposition products volatilized and/or decomposed further over a broad range of temperatures. It is possible that the material reacted with itself in a variety of ways leading to the range of volatilization and/or decomposition products and thereby temperatures observed. Although the material is monomeric, with only one epoxide moiety, oligomerization and polymerization are possible, as well as dimerization.

Example 9 Preparation and Analysis of n-Hexyl Carborane/Epoxies, Etc., Epoxy Nanocomposites Preparation of N-Hexyl Carborane/Epoxies, Etc., Epoxy Nanocomposites

As noted above, the Epoxies, Etc., epoxy is an optically clear, two part material comprising a resin with an epoxy equivalent weight (EEW) of 230. The curative is an amine terminated polyether based on polypropylene oxide. In preparing the nanocomposite, n-hexyl carborane was mixed into the epoxide in three different ways. First, the n-hexyl carborane was mixed into the resin, which was then thoroughly blended with the curative (“Resin” mix protocol). Second, n-hexyl carborane was mixed with the curative and then blended with the resin (“Catalyst” mix protocol). Finally, the n-hexyl carborane was added to the blended resin/curative mixture (“Epoxy” mix protocol). In all cases, the mixtures were allowed to cure in small aluminum foil cups at room temperature for over 48 hours. Some materials were cured at elevated temperatures (100° C.) for 1 hour. For comparison, 50 weight percent composites were cured at room temperature and elevated temperatures (100° C.) for 1 hour (Table 2). The resulting materials were homogeneous, clear, and colorless. As the n-hexyl carborane content increased, the materials become more elastomeric. The epoxy did not cure with 75 weight percent n-hexyl carborane. The compositions and mix protocol employed for each sample prepared in this Example are provided in Table 2, below:

TABLE 2 n-Hexyl Carborane/Epoxies, Etc., Epoxy Nanocomposites n-Hexyl Carborane Boron Mix Cure Sample ID (wt %) (wt %) Protocol Protocol NHC/EEE-1 10 4.7 Epoxy Room Temp. NHC/EEE-2 10 4.7 Catalyst Room Temp. NHC/EEE-3 10 4.7 Resin Room Temp. NHC/EEE-4 25 11.8 Epoxy Room Temp. NHC/EEE-5 25 11.8 Catalyst Room Temp. NHC/EEE-6 25 11.8 Resin Room Temp. NHC/EEE-7 50 23.7 Epoxy Room Temp. NHC/EEE-8 50 23.7 Catalyst Room Temp. NHC/EEE-9 50 23.7 Resin Room Temp. NHC/EEE-10 50 23.7 Epoxy Oven Cure NHC/EEE-11 50 23.7 Catalyst Oven Cure NHC/EEE-12 50 23.7 Resin Oven Cure NHC/EEE-13 75 35.7 Epoxy Oven Cure NHC/EEE-14 75 35.7 Catalyst Oven Cure NHC/EEE-15 75 35.7 Resin Oven Cure Analysis of n-Hexyl Carborane/Epoxies Etc. Epoxy Nanocomposites

DSC Analysis

Regardless of how the n-hexyl carborane was incorporated into the Epoxies, Etc. matrix, increasing amounts of n-hexyl carborane plasticized the material, as observed by the change in the glass transition temperature by DSC. All of the samples were cured at room temperature, except for the 75 weight percent sample (NHC/EEE-13), which was oven cured for 1 hour at 100° C. The sample containing 75 weight percent n-hexyl carborane was observed to have its Tg shifted lower by over 43° C. Even at room temperature, this material had structural integrity, was nearly optically clear, and contained over 35 weight percent boron.

The method by which the n-hexyl carborane was incorporated, either first into the resin, curative, or a mixture of the two, appears to have made little difference in the how the final material was plasticized, according to DSC analysis. Curing the material at room temperature for longer periods of time or at elevated temperatures for shorter periods also made little difference. In all cases, the glass transition temperatures dropped. Taken as a whole, the relatively smooth drop in Tg across all of the data was consistent with little or no n-hexyl carborane having volatilized.

Shore A Hardness

Each of the n-hexyl carborane nanocomposites were tested as outlined above for shore A hardness. The shore A hardness results indicated that the method by which the material was mixed caused subtle differences in the hardness of the final composite materials. The samples containing 10 weight percent n-hexyl carborane all had shore A hardness values similar to the control. In this case, when first mixed into either the catalyst or especially the resin, the shore A hardness was greater than the control. The result of this test was repeatable, but the cause is unknown. The rest of the samples become increasingly softer as n-hexyl carborane was added, which is consistent with the DSC data. In general, when the n-hexyl carborane was first mixed into the curative or catalyst, a stiffer composite was created, all else being equal.

Thermogravimetric Analysis

According to thermogravimetric analysis, the control Epoxies, Etc., epoxy had the highest T₅ temperature (i.e., the temperature at which 5 weight percent of the sample has been volatilized). The presence of n-hexyl carborane created two transitions, the first between ˜150° C. and ˜250° C., and the second between ˜300° C. and ˜450° C. Despite universally lower T₅ temperatures, nearly 75 percent of the 10 weight percent composite remained at ˜375° C. In fact, the final transitions of all of the materials were higher than the control. Compared to TGA analysis of the urethane composite with n-hexyl carborane, epoxy composites with n-hexyl carborane appeared to be preferentially thermally stabilized at high temperatures.

Example 10 Preparation and Analysis of n-Hexyl Carborane/Model Epoxy Nanocomposites Preparation of N-Hexyl Carborane/Model Epoxy Nanocomposites

As noted above, the Model Epoxy formulation, which is clear, but slightly colored, was based on EPON 828 resin and the curative EPIKURE 3270, which is a modified aliphatic amine. In this Example, n-hexyl carborane was mixed with the resin and curative, which were all thoroughly blended. Prior to curing at 75° C. for over 1 hour, small amounts of the material were poured into disk shaped RTV silicone molds (diameter=11 mm by 3.6 mm). The resulting materials where homogeneous, clear, and pale yellow colored. The compositions and mix protocol employed for each sample prepared in this Example are provided in Table 3, below:

TABLE 3 n-Hexyl Carborane/Model Epoxy Nanocomposites n-Hexyl Carborane Boron Mix Cure Sample ID (wt %) (wt %) Protocol Protocol NHC/ME-1 1 0.47 Resin Oven Cure NHC/ME-2 5 2.37 Resin Oven Cure NHC/ME-3 10 4.73 Resin Oven Cure NHC/ME-4 25 11.84 Resin Oven Cure NHC/ME-5 35 16.57 Resin Oven Cure NHC/ME-6 45 21.31 Resin Oven Cure NHC/ME-7 50 23.67 Resin Oven Cure NHC/ME-8 75 35.51 Resin Oven Cure Analysis of n-Hexyl Carborane/Model Epoxy Nanocomposites

Rheology

By rheology, n-hexyl carborane also clearly plasticizes the model epoxy based on EPON 828 and EPIKURE 3270. Like the Epoxies, Etc. matrix discussed above, the glass transition temperature of the model epoxy decreased with increasing n-hexyl carborane, as observed by the change in the tan δ. In the rheology plots (not shown) the areas under the tan δ peak for the 1 weight percent (NHC/ME-1) and 5 weight percent (MHC/ME-2) composites were also noticeably smaller than that of the control and composites with 10 weight percent n-hexyl carborane or greater.

Unlike with the Epoxies, Etc. matrix, where only one transition was observed by DSC even at very high n-hexyl carborane loadings, in the model epoxy matrix two transitions were observed with the samples having 5 weight percent n-hexyl carborane or more. The formation of a new peak or splitting of the existing peak is indicative of the formation of a separate material phase. The set of transitions both decreased with increasing n-hexyl carborane loading when the tan δ peak maximum temperature was plotted as a function of carborane loading. Additionally, one of the phases appeared to plateau at loadings above 45 weight percent.

Shore A Hardness

By rheology, n-hexyl carborane clearly plasticized the model epoxy matrix. However, the shore A hardness of composites with low loadings (1 to 10 weight percent) were equal or slightly stiffer than the control. All of the samples with n-hexyl carborane loadings greater than 25 weight percent were too soft to obtain shore A hardness data. The transition from stiff composites to those too soft to measure by shore A hardness occurred somewhere between materials with 10 and 25 weight percent n-hexyl carborane. It was also at this loading level that the single Tg began to separate into two phases, one with a much lower Tg. Though not wishing to be bound by theory, it is thought that this phase separation may contribute to the softness of the composites with greater than 10 weight percent n-hexyl carborane.

Thermogravimetric Analysis

TGA analyses of the model epoxy composites containing n-hexyl carborane show that the thermal stability of 1 weight percent (Sample NHC/ME-1) and 5 weight percent (Sample NHC/ME-2) composites were equal to or greater than the control. Even the T₅ temperature of the 5 weight percent sample was higher than the control. The increased thermal stability of these composites was easily observed in the difference between the T₁₅ temperature of the control (˜260° C.) and that of the 5 weight percent material (˜340° C.), which is approximately 80° C. higher. In contrast to composites based on the Epoxies, Etc. matrix, these samples all exhibited one transition. Multiple phases by rheology do not translate to the TGA results. Over all, these composites had a slightly lower ultimate thermal stability compared to the Epoxies, Etc. materials. At higher temperatures the Model epoxy composites were similar to those based on the Epoxies, Etc. matrix in that they were significantly more stable than the n-hexyl carborane composites based on EN8 polyurethane matrices.

Example 11 Preparation and Analysis of Carborane Epoxy/Model Epoxy Polymers Preparation of Carborane Epoxy/Model Epoxy Polymers

As with the n-hexyl carborane, the carborane epoxy was mixed into the resin, which was then blended with the curative. In this Example, the carborane epoxy did not replace the EPON 828 epoxide, but was rather added to it on a weight basis. After blending, the samples were cured at 75° C. for 1 hour. Thereafter, small amounts of the material were poured into RTV silicon molds (diameter=11 mm by 3.6 mm). As the carborane epoxy content increased, increased amounts of air appeared to be entrained in the material, giving it a creamy, foam-like appearance. Upon curing, these materials foamed, significantly at higher carborane epoxy loadings. Samples with 25 weight percent and 45 weight percent carborane epoxy were remade, and degassed in vacuo just after being mixed and prior to being cured. Degassing the samples significantly reduced foaming upon curing. These, like the rest of the materials where rigid, opaque, and white. The compositions and mix protocol employed for each sample prepared in this Example are provided in Table 4, below:

TABLE 4 Carborane Epoxy/Model Epoxy Polymers Carborane Epoxy Boron Mix Cure Sample ID (wt %) (wt %) Protocol Protocol CE/ME-1 1 0.54 Resin Oven Cure CE/ME-2 5 2.70 Resin Oven Cure CE/ME-3 10 5.40 Resin Oven Cure CE/ME-4* 25 13.50 Resin Oven Cure CE/ME-5 35 19.17 Resin Oven Cure CE/ME-6* 45 24.30 Resin Oven Cure CE/ME-7 50 27.00 Resin Oven Cure *These samples were remade using the degassing procedures described above.

Analysis of Carborane Epoxy/Model Epoxy Polymers Rheology

Since carborane epoxy is monofunctional compared to BADGE, which is difunctional, carborane epoxy was not used as a replacement for BADGE in the formulations, but was rather added to the control formulation on a weight basis. As noted above, as the carborane epoxy content increased, air appeared to be increasingly whipped into the material upon mixing. The carborane epoxy is an off-white waxy solid at room temperature and pressure. These materials foamed when cured, significantly at higher carborane epoxy loadings. Only the samples prepared with 10 weight percent carborane epoxy or less were acceptable for rheology. Samples with 25 and 45 weight percent carborane epoxy were remade, only this time they were degassed in vacuo prior to curing. Degassing the samples significantly reduced foaming upon curing, producing samples amenable to rheological testing. These additional samples, like the rest of the materials, were fully cured, rigid, opaque, and white.

An examination of the tan δ peak maximums showed that, after an initial drop in temperature of only ˜12° C., the Tgs leveled off and begin to increase. Ultimately, at 45 weight percent carborane epoxy, the Tg was nearly equal to that of the control and was higher than every other formulation. In general, the primary Tg was relatively unaffected. At 45 weight percent, a shoulder was observed on the low temperature side of the main transition at ˜35° C. Depending on the volume of this phase, it might be expected to soften the composite.

As noted above, it was discovered after preparing the carborane epoxy/model epoxy polymers that the carborane epoxy had degraded to approximately 87 percent purity. This degradation may have resulted in the formation of decomposition products, such as dimers and oligomers of the carborane epoxy. Thus, it is unclear whether the initial plasticization was due to the reacted carborane epoxy tied into the matrix, free unreacted carborane epoxy, decomposition products, or some combination thereof.

Shore A Hardness

The shore A hardness values for the model epoxy control, 1, 5, and 10 weight percent samples (Samples CE/ME-1 to -3), and the remade and degassed 25 and 45 weight percent samples (Samples CE/ME-4 and -6) were all similar and relatively stiff (all between about 78 A and 98 A). The 1 through 10 weight percent samples exhibited little change in hardness, but the degassed 25 weight percent sample was actually stiffer than the control. Unlike with rheology, the presence of foam might be expected to affect the shore A hardness results, even for relatively rigid foams. Though not wishing to be bound by theory, this may explain why the first three samples were softer than the control, but were less stiff than the 25 weight percent sample, which was degassed and was therefore less foam-like. If true, then the relatively high glass transition temperature for the 45 weight percent sample and the relatively high stiffness of both the degassed 25 and 45 weight percent samples may indicate reinforcement. Additionally, the formation of a second, lower Tg phase in the 45 weight percent sample may have caused that sample to be softer than what might otherwise be expected.

Thermogravimetric Analysis

TGA analyses of the carborane epoxy/model epoxy polymers showed that the T₅ temperature for all the samples was lower than that of the control. The TGA data also showed a steady increase in the high temperature (greater than 350° C.) stability of the samples from 1 to 10 weight percent, and a plateau as the carborane epoxy content increased to greater than 25 weight percent. In general, this was an indication of the presence of increasing amounts of carborane and was due to, at least in part, the inorganic nature of carboranes. More material was left at 490° C. than can be explained based purely on the inorganic content of the carborane. This is especially true for the 25 weight percent sample. These composite materials appeared to follow the general trend that epoxies are preferentially stabilized at high temperatures compared to EN8 urethane, discussed below.

Example 12 Preparation and Analysis of n-Hexyl Carborane/EN8 Urethane Nanocomposites

Preparation of n-Hexyl Carborane/EN8 Urethane Nanocomposites

As discussed above, EN8 is a two part polyurethane, consisting of a Part A and Part B, which is clear, and orange colored. Part A contains ˜88 to 90 weight percent of a toluenediisocyanate (“TDI”) end-capped polybutadiene and ˜10 to 12 weight percent TDI. Part B is 50 weight percent bis-(2-hydroxypropyl) aniline (“BHPA”), 50 weight percent 2-ethyl-1,3-hexane diol (“EHD”), and the catalyst. n-Hexyl carborane was first blended with Part A, which was then blended with Part B. All materials were degassed in vacuo and small amounts of the material were poured into disk shaped RTV silicone molds (diameter=˜11 mm by 3.6 mm). The composite materials were cured at 100° C. for 1 hour. The resulting materials were homogeneous, clear, and orange. The composites softened and become lighter colored orange with increasing n-hexyl carborane loadings. A 75 weight percent n-hexyl carborane formulation did not cure and remained a liquid mixture. The concentrations employed for each sample prepared in this Example are provided in Table 5, below:

TABLE 5 n-Hexyl Carborane/EN8 Urethane Nanocomposites n-Hexyl n-Hexyl Carborane Carborane Boron Part A Part B Sample ID (wt %) (g) (wt %) (g) (g) NHC/EN8-1 1 0.17 0.47 14.58 2.74 NHC/EN8-2 2.5 0.44 1.18 14.36 2.70 NHC/EN8-3 5.0 0.88 2.37 14.00 2.63 NHC/EN8-4 10 1.75 4.73 13.25 2.49 NHC/EN8-5 15 2.55 7.10 12.16 2.29 NHC/EN8-6 25 4.38 11.84 11.05 2.08 NHC/EN8-7 35 5.95 16.57 9.30 1.75 NHC/EN8-8 45 7.65 12.30 7.87 1.48 NHC/EN8-9 50 8.51 23.67 7.16 1.35 Analysis of n-Hexyl Carborane/EN8 Urethane Nanocomposites

Rheology

As noted above, EN8 urethane consists of two primary components: a lightly cross-linked, soft, and rubbery polybutadiene (“PBD”) phase (Part A), and a crystalline, cross-linked, and rigid urethane phase (Part B). This was apparent from two major glass transitions observed rheologically via tan δ. The lower temperature transition was associated with the PBD segments, and the high temperature transition with those of the urethane. All of these composite materials were clear and homogeneous. They were also decreasingly orange colored as the catalyst was diluted by the addition of n-hexyl carborane.

Closer examination of the lower-temperature tan δ peaks of the PBD segments showed that, in general, this segment was reinforced by the addition of n-hexyl carborane. Although the total change in the peak tan δ temperature was relatively small (˜15 to 17° C.), it appeared to be increasing. The changes in storage modulus (G′, Pa) and loss modulus (G″, Pa) led to the same conclusion, namely that addition of n-hexyl carborane caused the PDB segments of EN8 urethane to be reinforced. Results from these analyses indicated increased storage and loss moduli values associated with increased n-hexyl carborane content. It should be noted that there was some variation in the data, and some of the data points were out of order. This variation in the data may have been caused by variation in the samples, in particular variation in sample thickness.

In addition, a new lower temperature tan δ peak formed after ˜10 weight percent n-hexyl carborane had been added. This new peak also increased in temperature indicating reinforcement as the amount of n-hexyl carborane increased. This was somewhat unexpected; n-hexyl carborane has been studied in conjugated diene elastomers, including hydroxy-terminated polybutadiene and has been found to be an effective plasticizer.

Depending on the volume, a new phase within the PBD segments at a lower temperature, even if it increases in temperature as more carborane is added, could have a net effect on the physical properties of the material. All things being equal, such materials, for example, might be expected to be softer than the control, until such a loading is reached that the lowest temperature Tg is higher in temperature than that of the control. Again, this would be dependent on the volume of the new phase being large enough. For the PBD segments, this point was reached at ˜25 weight percent n-hexyl carborane. At 35 weight percent, the lowest Tg of the PBD segments was higher than that of the control. So, compared to the control, the PBD segments were reinforced.

With the urethane segments, which have a higher temperature, the effect of n-hexyl carborane is much different. Initially, two broad tan δ transitions were observed, which steadily decreased in temperature as more n-hexyl carborane was added. The Tg of the urethane segments moving to lower temperatures with increased n-hexyl carborane content is consistent with plasticization. At about 45 weight percent and clearly at 50 weight percent n-hexyl carborane, a third tan δ transition was observed at very high temperatures. This peak also appeared to lower in temperature as the amount of n-hexyl carborane increases.

As with the PBD segments, but in reverse, depending on the volume, a new phase within the urethane segments at a higher temperature could also have a net effect on the physical properties of the material. If the new high Tg phase first formed at 45 weight percent n-hexyl carborane was large enough, it could cause the composite to be reinforced compared to the control. However, the area of the highest Tg was smaller than that of main transition in the 45 and 50 weight percent composites, which was at a significantly lower temperature.

Shore A Hardness

When n-hexyl carborane was added to EN8 urethane, in general, the PBD segments were reinforced. Conversely, the urethane segments were plasticized. The global impact of these opposing effects on the physical properties of the composites can be seen in the Shore A Hardness data, depicted in FIG. 12. As can be seen in FIG. 12, the hardness of the nanocomposites decreased gradually with increasing n-hexyl carborane. After more than about 35 weight percent has been added, the composites became too soft for shore A testing. The relatively small increase in the Tg of the PBD segments was more than compensated for by the decrease in the Tg of the urethane portion of the materials. The shore A hardness of these samples was tracked as a way of determining if n-hexyl carborane was volatilizing out of the materials over time. Some increase in stiffness was observed, especially at high loadings, which is what would be expected if n-hexyl carborane had the net effect of plasticizing EN8 urethane. Additional testing, even at high loading, showed that the stiffness did not continue to increase, but leveled off. It seems likely that a small initial loss of n-hexyl carborane occurred, especially at higher loadings, in combination with a small amount of additional curing over time.

Dynamic Mechanical Analyzer (“DMA”) Analyses

Another measure of the global physical properties of the n-hexyl carborane/EN8 urethane nanocomposites was made via DMA analysis. When the DMA results were analyzed, low levels of n-hexyl carborane appeared to have little effect, if not slightly increase the dynamic stiffness of the composites. In these analyses, the control, the 1 weight percent, and the 2.5 weight percent n-hexyl carborane samples were of similar overlapping stiffness. Again, at higher n-hexyl carborane loadings, the effect of plasticization dominated and the materials became softer.

Thermogravimetric Analysis

TGA analyses of the n-hexyl carborane/EN8 urethane nanocomposites showed that the thermal stability of the 1 and 2.5 weight percent composites were nearly equal to, and at some temperatures slightly greater than, the control. Although the T₅ in these analyses was the highest for the control, the 1 to 10 weight percent samples exhibited thermal stability that was very similar to the control. Even at high temperatures, no additional thermal stability was imparted to the composite. The TGA analyses were carried out to a maximum temperature of over 630° C. When compared to the thermal stability of the n-hexyl carborane/model epoxy nanocomposites (Example 10), only about 10 percent of the material remained. The thermal stability profiles of these materials did resemble those of the n-hexyl carborane/model epoxy composites, in that increasing amounts of n-hexyl carborane gradually lowered the thermal stability, which is consistent with volatilization. This result is also consistent with some n-hexyl carborane volatilizing out of the composites over time, especially at high loadings, as may be indicated by the shore A hardness data over time (FIG. 12).

Example 13 Preparation and Analysis of Carborane Diol/EN8 Urethane Polymers Preparation of Carborane Diol/EN8 Urethane Polymers

As discussed above, EN8 is a two part urethane, consisting of a Part A and Part B, which is clear, and orange colored. Part A contains ˜88 to 90 weight percent of a toluenediisocyanate (“TDI”) end-capped polybutadiene and ˜10 to 12 weight percent TDI. Part B is 50 weight percent bis-(2-hydroxypropyl) aniline (“BHPA”), 50 weight percent 2-ethyl-1,3-hexane diol (“EHD”), and the catalyst. Carborane diol was first blended with Part A, which was then blended with Part B. In this Example, carborane diol increasingly replaced Part B on a weight basis. The 19.3 weight percent sample (CD/EN8-5), shown in Table 6, below, contained no Part B. To make up for the resulting loss of catalyst, a drop of ENA was added to this sample to provide catalyst. All materials were degassed in vacuo and small amounts of the material were poured into disk shaped RTV silicone molds (diameter=˜11 mm by 3.6 mm). The composite materials were cured at 100° C. for 1 hour. The resulting materials became increasingly opaque and lighter orange with increasing carborane diol. The 19.3 weight percent sample was opaque and white/orange. The concentrations employed for each sample prepared in this Example are provided in Table 6, below:

TABLE 6 Carborane Diol/EN8 Urethane Polymers Carborane Diol Boron Part A Part B Sample ID (wt %) (wt %) (wt %) (wt %) CD/EN8-1 1.0 0.53 84.0 15.0 CD/EN8-2 2.5 1.32 83.6 13.9 CD/EN8-3 5.0 2.65 83.0 12.0 CD/EN8-4 10 5.29 81.9 8.1 CD/EN8-5 19.3 10.21 80.7 —

Analysis of Carborane Diol/EN8 Urethane Polymers Rheology

Like the EN8 formulations with n-hexyl carborane, the carborane diol samples also exhibit two main thermal transitions by rheology. Plots of tan δ for these materials showed one low temperature transition caused by the PDB segments and another by the cross-linked and highly crystalline urethane phase. It was apparent that neither transition shifted much in temperature as the carborane diol content increased. Even the sample that contained only carborane diol exhibited transitions that were very similar to those of the control and the rest of the samples. The size and molecular weight of carborane diol is similar (204.266 g/mol) to those of BHPA (181.225 g/mol) and EHD (144.206 g/mol). It may be possible that the insoluble carborane diol, soluble unreacted or reacted carborane diol, or a combination of the two are acting to reinforce and increase what would otherwise be a plasticized and lowered set of Tgs.

Only the 1 weight percent carborane diol sample was homogenous. The rest of the composite materials contained insoluble carborane diol, which is a white crystalline solid with a melt point of about 80° C. (by DSC). By SEM at 300× magnification, shown in FIGS. 13 a and 13 b, the crystalline carborane diol was found in two forms: (1) agglomerates of smaller crystals, and (2) large single crystals. As a result, these composite materials were off-white and opaque. The image in FIG. 13 a shows the agglomerates of smaller crystals. The image in FIG. 13 b shows the cavity left by a large single crystal, which was removed when the sample was prepared for imaging. Numerous large crystals could be seen below the surface, but no crystals could be found and imaged protruding from the surface. It is interesting to note that the bulk carborane diol did not contain large single crystals like the one observed in the SEM image in FIG. 13 b. This may be an indication of recrystallization. In both cases, it is unlikely that either solid would be significantly reinforcing. The smaller crystals were poorly dispersed and the large crystals had low relative surface areas, despite their large aspect ratios. Furthermore, the rest of the sample appeared to be homogeneous as can be seen in the field around the crystals.

Shore A Hardness

The shore A hardness of the carborane diol/EN8 urethane polymers indicated that they were all of similar high stiffness (between about 80 A and 90 A). The carborane diol became insoluble at loadings as low as 2.5 weight percent. It is unlikely that much carborane diol is soluble in EN8 beyond what would be solubilized by the driving force of being reacted into the polymer matrix. It may be possible that the polymer network formed incorporating carborane was stiffer than the same material containing the organic diols, but at what may have been a lower cross-link density. These composites were considerably stiffer than the EN8 composites with n-hexyl carborane (see FIG. 12).

Dynamic Mechanical Analyzer Analyses

The results of DMA analysis were consistent with those of shore A hardness testing. All of the samples were of similar stiffness, most being slightly stiffer than the control.

Thermogravimetric Analyses

As discussed above, n-hexyl carborane is incapable of reacting with the EN8 matrix and, by TGA, those composites showed little improvement in thermal stability. TGA analyses of the carborane diol composites also showed materials all with similar profiles. Unlike n-hexyl carborane, the carborane diol composites showed increasing thermal stability at high temperatures. This is consistent with carborane diol being incorporated into the matrix. In fact, the 19.3 weight percent carborane diol sample exhibited thermal stability that was improved compared to the control over much of the temperature range.

Carborane diol seems to have been solubilized, with its reaction with isocyanate and incorporation into the polymer matrix being the likely driving force. It would appear that not much more than what was being drawn in by this mechanism was solubilized in light of the presence of recrystallized carborane diol. The carborane diol that remained insoluble was not likely to be reinforcing. It is not possible to differentiate between the inherent stiffness of a new carborane containing urethane with a relatively low cross-link density and a new carborane containing urethane that is also significantly reinforced by a small amount of soluble, but unreacted carborane diol. A urethane that contained carborane within its network might be expected to have a greater solubility for additional carborane. Furthermore, the relatively polar carborane diol might be expected to be more soluble in the urethane component of the polymer compared to the PBD segments, which is where a reaction would need to occur.

Example 14 Glass Transition Temperature Comparison for Nanocomposites

Example 14 describes the incorporation of four unreactive boron cage compounds into four polyolefin elastomers of differing compositions, for a total of 16 samples. The change in glass transition temperature (“Tg”) upon addition of the BCCs in relation to the unmodified polyolefin elastomers was then compared.

Test Procedure

In the following Example 14, nanocomposite test samples were subject to rheology characterization testing. The following procedure was employed. A TA Instruments AR-G2 rheometer was used to determine rheological properties of samples using temperature sweeps with constant strain and frequency. The testing was performed under torsion between 25 mm diameter parallel plates. As much as possible, disks (diameter ˜12.5 mm by ˜3.25 mm thick) of uniform size were used as samples. Using a 12.5-mm die, samples were cut from pressed sheets. All samples were subjected to temperature sweeps with temperature ramp rate of 2.5 or 5° C./minute, at strains of 0.05%, and a frequency of 1 Hz. All experiments were performed under normal force control at 5.0 N, with a 0.5 N tolerance (gap=+/−500 μm).

Materials Used

Poly(ethylene-co-vinyl acetate) (“EVA”) was prepared by dissolution methods of two EVA copolymers to obtain a composition of 42% vinyl acetate and 58% ethylene. Evatane® 33-400 was purchased from Arkema Inc. and Levamelt® 456 was obtained from Lanxess Corporation. Poly(ethylene-co-vinyl acetate-co-vinyl alcohol) terpolymer (“EVA-OH”) was synthesized by the base catalyzed alcoholysis reaction of the EVA blend. The result of this reaction is a drop in the vinyl acetate content to yield an EVA-OH terpolymer with a composition of 58% ethylene, 36% vinyl acetate, and 6% vinyl alcohol. Poly(ethylene-co-octene) (“PEO”) was purchased from Dow Chemical Company as ENGAGE™ 8200. Poly(ethylene-co-ethyl acrylate) (“PEEA”) having 19.5% ethyl acrylate and 80.5% ethylene monomer contents was also purchased from Dow Chemical Company as AMPLIFY™ EA 103. The four boron cage compounds used were dilithium dodecahydrododecaborane (Li₂[B₁₂H₁₂]), 1,2-bis-(hydroxymethyl)-o-carborane (“carborane diol”), 1,3-di-o carboranylpropane (“tethered carborane”), and n-hexyl-o-carborane (“n-hexyl carborane”). All of the BCCs used were synthesized by the International Institute of Nano and Molecular Medicine at the University of Missouri-Columbia, using procedures described above in Example 2.

Sample Preparation

20-30 grams of BCC nanocomposite samples were prepared by dissolution techniques. Polymers were dissolved in ˜200 mL tetrahydrofuran (“THF”). While EVA and EVA-OH solutions were made by stirring at room temperature, PEO and PEEA solutions needed to be heated to near the boiling point of THF. The BCC was dissolved separately in THF and added to the dissolved polymer solution. The nanocomposite solutions were then poured into TEFLON® lined pans and allowed to air dry. Once the majority of the THF had evaporated, the resulting solid film was heated in a convection oven at 70° C. for 3 hours to remove any residual THF. The samples were then melt pressed into sheets nominally 3.2 to 3.3 mm thick.

Results

Each of the four polymer systems (PEO, PEEA, EVA, and EVA-OH) were loaded individually with 10 weight % of the four boron cage compounds, thereby producing 16 samples. Changes in the Tg of the resulting nanocomposites can be easily detected and a determination made whether the polymer matrix was reinforced or plasticized. A plasticizer will decrease the Tg of the polymer, while a filler that reinforces will cause the opposite to occur, an increase. In dynamic mechanical tests, like the torsion rheology test used here, the Tg can be defined as the temperature where the loss modulus or the tan δ go through a maximum. These maxima are not exactly the same temperature, but either can be used to define the Tg. For this Example, the loss modulus maximum was used to define the Tg. The glass transition temperatures for the unmodified polymers were found to be: PEO, −53.0° C.; PEEA, −32.7° C.; EVA, −33.2° C.; and EVA-OH, −31.9° C. The changes in glass transition temperature from the baseline for each BCC/polymer combination are given as a bar chart in FIG. 14. All of the n-hexyl carborane samples showed a decrease in Tg and were therefore clearly plasticized. The carborane diol samples produced relatively small changes from the baseline polymers. For EVA and EVA-OH systems, the presence of carborane diol resulted in slightly higher Tgs, but for PEO and PEEA samples, lower values were found. The same trends were found upon incorporation of tethered carborane (higher Tg in EVA and EVA-OH and lower Tg in PEO and PEEA); however, the shifts and differences were larger than observed for the carborane diol. Finally, the most dramatic effect was found upon the addition of Li₂[B₁₂H₁₂]. EVA, EVA-OH, and PEEA were significantly reinforced by Li₂[B₁₂H₁₂] as demonstrated by large shifts in the glass transition temperatures and increased mechanical strength (storage and loss modulus). Interestingly, PEO was not reinforced by Li₂[B₁₂H₁₂], but slightly plasticized. In fact, PEO was plasticized by all four BCCs.

Example 15 Preparation of Carborane Diol/Carborane Bisepoxy Polymer

A polymer was prepared by weighing carborane diol and carborane bisepoxy into an aluminum foil pan in the amounts indicated in Table 7, below, and thoroughly blending them at room temperature by hand using a standard wooden tongue depressor split the long way. Carborane bisepoxy was also tested by itself. Small amounts of the material were poured into RTV silicone molds for testing, in addition to the material that remained in the aluminum foil pan. The reactive mixtures and carborane bisepoxy were then heated at 150° C. for 2 hours. Prior to curing, the mixtures were observed to be opaque, off-white blends. After curing, hard, brittle, tan/brown solids had formed indicating that polymerization had taken place.

TABLE 7 Carborane Diol/Carborane Bisepoxy Formulations Carborane Carborane Boron Content Sample ID Bisepoxy (g) Diol (g) BRR* (wt %) CD/CB-1 4.30 3.71 1:1   49.05 CD/CB-2 4.42 3.59 1:1.05 48.94 CD/CB-3 4.22 3.79 1:0.95 49.12 CD/CB-4 5.00 0.00 N/A 45.71 *BRR represents the ratio of amine protons to epoxide moieties.

Example 16 Preparation of Carborane Diol/BADGE Polymer

A carborane diol/bisphenol A diglycidyl ether (“BADGE”) polymer was prepared by weighing the BADGE and carborane diol into an aluminum foil pan in the amounts indicated in Table 8, below, and thoroughly blending them at room temperature by hand using a standard wooden tongue depressor split the long way. Small amounts of the material were poured into RTV silicone molds for testing, in addition to the material that remained in the aluminum foil pan. The reactive mixture was then heated at 150° C. for 2 hours. Prior to curing, the mixture was observed to be an opaque, off-white blend. After curing, a tan/brown hard solid had formed indicating that polymerization had taken place.

TABLE 8 Carborane Diol/BADGE Formulations BADGE Carborane Boron Content Sample ID (g) Diol (g) BRR* (wt %) CD/BADGE-1 5.04 2.96 1:1   19.60 CD/BADGE-2 5.13 2.87 1:1.05 18.99 CD/BADGE-3 4.95 3.06 1:0.95 20.23 *BRR represents the ratio of amine protons to epoxide moieties.

Example 17 Preparation of Carborane Bisepoxy/MDA Polymer

A carborane diol/4,4′-methylenedianiline (“MDA”) polymer was prepared by weighing the carborane bisepoxy and MDA into an aluminum foil pan in the amounts indicated in Table 9, below, and thoroughly blending them at room temperature by hand using a standard wooden tongue depressor split the long way. Small amounts of the material were poured into RTV silicone molds for testing, in addition to the material that remained in the aluminum foil pan. The reactive mixture was then heated at 150° C. for 2 hours. Prior to curing, the mixture was observed to be an opaque, off-white blend. After curing, a tan/brown hard solid had formed indicating that polymerization had taken place. Note that in the table below, N is the number of amine groups in MDA divided by the number of epoxy groups in carborane bisepoxy.

TABLE 9 Carborane Bisepoxy/MDA Formulation Carborane MDA Boron Content Sample ID Bisepoxy (g) (g) BRR* N (wt %) CBE/MDA-1 4.30 1.86 1:1 1 47.89 *BRR represents the ratio of amine protons to epoxide moieties.

Example 18 Analyzing Effects of Li₂[B₁₂H₁₂] Salt on EVA-OH and EVA Polymers

In this procedure, 20-30 grams of EVA-OH or EVA were dissolved in 200 mL of tetrahydrofuran (THF) under stirring in an Erlenmeyer flask. In a separate container, Li₂[B₁₂H₁₂] salt was dissolved in additional THF at the desired levels, and then added to the Erlenmeyer flask. The entire solution was allowed to stir until completely homogenous. The solution was poured into a pan with a Teflon® liner and allowed to air dry. Once the majority of the THF had evaporated and the sample was solid, the resulting film was heated in a convection oven at 70° C. for 3 hours to remove any residual THF. The samples were then pressed into sheets at 100° C. in molds into 51 mm×51 mm squares nominally 3.2-3.3 mm thick. The samples were then post-cured at 120° C. in a convection oven for 24 hours. Some samples were stored in dessicated environments, and others which were stored in polyethylene bags and allowed to absorb moisture from the humidity in a general laboratory environment.

The glass transition temperatures of EVA-OH samples (5%, 10%, and 25% Li₂[B₁₂H₁₂]) were evaluated over time during exposure to atmospheric moisture and compared to a control. The glass transition temperatures were determined. These results are shown in FIG. 15.

The storage moduli of 10% Li₂[B₁₂H₁₂] EVA-OH samples after atmospheric exposure were evaluated at varying temperatures and compared to a control. The storage modulus was determined by the procedure described in Example 14. These results are shown in FIG. 16.

The tan δ of 10% Li₂[B₁₂H₁₂] EVA-OH samples after atmospheric exposure were evaluated at varying temperatures and compared to a control. The tan δ was determined by the procedure described in Example 14. These results are shown in FIG. 17.

The storage moduli of 10% Li₂[B₁₂H₁₂] EVA-OH samples after atmospheric exposure were evaluated at varying temperatures and compared to a control to show that the effect can be reversed with drying at elevated temperatures. The storage modulus was determined by the procedure described in Example 14. These results are shown in FIG. 18.

The tan δ of 10% Li₂[B₁₂H₁₂] EVA-OH samples after atmospheric exposure were evaluated at varying temperatures and compared to a control to show that the effect can be reversed. The tan δ was determined by the procedure described in Example 14. These results are shown in FIG. 19.

In summary, the above results show that the use of a hygroscopic salt can be used to fine-tune the properties of a polymer. Using this salt as a filler increased the glass transition temperature dramatically. If the polymer with salt filler is stored in an undessicated environment, the salt will cause moisture to be absorbed, and that moisture will act as a plasticizer. The material will become more flexible as water is absorbed. This effect can be reversed by drying the product, thus returning it to a more rigid state.

Selected Definitions

It should be understood that the following is not intended to be an exclusive list of defined terms. Other definitions may be provided in the foregoing description accompanying the use of a defined term in context.

As used herein, the terms “a,” “an,” and “the” mean one or more.

As used herein, the term “and/or,” when used in a list of two or more items, means that any one of the listed items can be employed by itself or any combination of two or more of the listed items can be employed. For example, if a composition is described as containing components A. B, and/or C, the composition can contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination.

As used herein, the terms “comprising,” “comprises,” and “comprise” are open-ended transition terms used to transition from a subject recited before the term to one or more elements recited after the term, where the element or elements listed after the transition term are not necessarily the only elements that make up the subject.

As used herein, the terms “containing,” “contains,” and “contain” have the same open-ended meaning as “comprising,” “comprises,” and “comprise” provided above.

As used herein, the terms “having,” “has,” and “have” have the same open-ended meaning as “comprising,” “comprises,” and “comprise” provided above.

As used herein, the terms “including,” “includes,” and “include” have the same open-ended meaning as “comprising,” “comprises,” and “comprise” provided above.

Numerical Ranges

The present description uses numerical ranges to quantify certain parameters relating to various embodiments of the invention. It should be understood that when numerical ranges are provided, such ranges are to be construed as providing literal support for claim limitations that only recite the lower value of the range as well as claim limitations that only recite the upper value of the range. For example, a disclosed numerical range of 10 to 100 provides literal support for a claim reciting “greater than 10” (with no upper bounds) and a claim reciting “less than 100” (with no lower bounds).

The present description uses specific numerical values to quantify certain parameters relating to the invention, where the specific numerical values are not expressly part of a numerical range. It should be understood that each specific numerical value provided herein is to be construed as providing literal support for a broad, intermediate, and narrow range. The broad range associated with each specific numerical value is the numerical value plus and minus 60 percent of the numerical value, rounded to two significant digits. The intermediate range associated with each specific numerical value is the numerical value plus and minus 30 percent of the numerical value, rounded to two significant digits. The narrow range associated with each specific numerical value is the numerical value plus and minus 15 percent of the numerical value, rounded to two significant digits. For example, if the specification describes a specific temperature of 62° F., such a description provides literal support for a broad numerical range of 25° F. to 99° F. (62° F.+/−37° F.), an intermediate numerical range of 43° F. to 81° F. (62° F.+/−19° F.), and a narrow numerical range of 53° F. to 71° F. (62° F.+/−9° F.). These broad, intermediate, and narrow numerical ranges should be applied not only to the specific values, but should also be applied to differences between these specific values. Thus, if the specification describes a first pressure of 110 psia and a second pressure of 48 psia (a difference of 62 psi), the broad, intermediate, and narrow ranges for the pressure difference between these two streams would be 25 to 99 psi, 43 to 81 psi, and 53 to 71 psi, respectively.

Claims not Limited to Disclosed Embodiments

The preferred forms of the invention described above are to be used as illustration only, and should not be used in a limiting sense to interpret the scope of the present invention. Modifications to the exemplary embodiments, set forth above, could be readily made by those skilled in the art without departing from the spirit of the present invention.

The inventors hereby state their intent to rely on the Doctrine of Equivalents to determine and assess the reasonably fair scope of the present invention as it pertains to any apparatus not materially departing from but outside the literal scope of the invention as set forth in the following claims. 

What is claimed is:
 1. A method of adjusting the properties of a material, said method comprising: providing a composition comprising: a matrix comprising a polymer; and a filler comprising a hygroscopic salt; and exposing said composition to moisture under conditions for said composition to absorb said moisture.
 2. The method of claim 1, wherein said composition has a first glass transition temperature prior to said exposing, and a second glass transition after said exposing, said first glass transition temperature being at least about 1° C. greater than said second glass transition temperature within about 1 day after said exposing was begun.
 3. The method of claim 1, wherein said composition has a first glass transition temperature prior to said exposing, and a second glass transition after said exposing, said first glass transition temperature being at least about 10° C. greater than said second glass transition temperature within about 1 day after said exposing was begun.
 4. The method of claim 1, wherein said composition has a first glass transition temperature prior to said exposing, and a second glass transition after said exposing, said first glass transition temperature being from about 10° C. to about 100° C. greater than said second glass transition temperature within about 7 days after said exposing was begun.
 5. The method of claim 1, wherein said composition has a first glass transition temperature prior to said exposing, and a second glass transition after said exposing, said first glass transition temperature being from about 30° C. to about 100° C. greater than said second glass transition temperature within about 28 days after said exposing was begun.
 6. The method of claim 1, wherein said composition has a first storage modulus at room temperature prior to said exposing, and a second storage modulus at room temperature after said exposing, said second storage modulus being at least about 40% lower than said first storage modulus within about 1 day after said exposing was begun.
 7. The method of claim 1, wherein said composition has a first storage modulus at 0° C. prior to said exposing, and a second storage modulus at 0° C. after said exposing, said second storage modulus being at least about 30% lower than said first storage modulus within about 1 day after said exposing was begun.
 8. The method of claim 1, wherein said composition has a first storage modulus at −25° C. prior to said exposing, and a second storage modulus at −25° C. after said exposing, said second storage modulus being at least about 10% lower than said first storage modulus within about 1 day after said exposing was begun.
 9. The method of claim 1, said filler consisting essentially of said hygroscopic salt.
 10. The method of claim 9, said filler consisting of said hygroscopic salt.
 11. The method of claim 1, said filler comprising a cage compound selected from the group consisting of a borane cage compound, a carborane cage compound, a metal complex thereof, a residue thereof, mixtures thereof, and agglomerations thereof, wherein said cage compound comprises at least 7 cage atoms, wherein said cage compound is not covalently bound to said polymer.
 12. The method of claim 1, wherein said filler comprises a cage compound selected from the group consisting of a borane cage compound, a carborane cage compound, a metal complex thereof, a residue thereof, mixtures thereof, and agglomerations thereof, wherein said cage compound comprises at least 7 cage atoms, wherein said cage compound comprises less than 95 weight percent of each of ortho-[1,2-dicarbadodecaborane], meta-[1,7-dicarbadodecaborane], para-[1,12-dicarbadodecaborane], and a compound having the following structure:

wherein R is an n-alkyl group, wherein said cage compound is not covalently bound to said polymer.
 13. The method of claim 1, said filler comprising a cage compound selected from the group consisting of: (a) a closo-carborane having the general formula C₂B_(n)H_(n+2), wherein n is in the range of from 5 to 10; (b) a closo-carborane having the general formula R_(x)[C₂H_(n+2−x)], wherein n is in the range of from 5 to 10, x is in the range of from 1 to 2, and each R is independently selected from the group consisting of a C₁ to C₂₀ n-alkyl, a hydroxy, a carboxy, an epoxy, an isocyanate, a primary amine, a silyl, and an alkoxy silyl; (c) a closo-carborane salt having the general formula [CB_(n)H_(n+1)]X, wherein n is in the range of from 6 to 11, and X is selected from the group consisting of Li⁺, Na⁺, K⁺, Cs⁺, and a quaternary ammonium; (d) a closo-carborane salt having the general formula R[CB_(n)H_(n)]X, wherein n is in the range of from 6 to 11, R is selected from the group consisting of a C₁ to C₂₀ n-alkyl, a hydroxy, a carboxy, an epoxy, an isocyanate, a primary amine, a silyl, and an alkoxy silyl, and X is selected from the group consisting of Li⁺, Na⁺, K⁺, Cs⁺, and a quaternary ammonium; (e) a closo-borane salt having the general formula [B_(n)H_(n)]X₂, wherein n is in the range of from 7 to 12, and X is selected from the group consisting of Li⁺, Na⁺, K⁺, Cs⁺, and a quaternary ammonium; (f) a closo-borane salt having the general formula [B_(n)H_(m) (OR)_(p)]X₂, wherein n is in the range of from 7 to 12, wherein m+p=n, with p being in the range of from 1 to 12, each R is independently selected from the group consisting of a hydrogen atom and an aliphatic group, and X is selected from the group consisting of Li⁺, Na⁺, K⁺, Cs⁺, and a quaternary ammonium; (g) a nido-carborane salt having the general formula R_(x)[C₂B₂H_(n+2−x)]X₂, wherein n is in the range of from 5 to 9, x is in the range of from 1 to 2, each R is independently selected from the group consisting of a C₁ to C₂₀ n-alkyl, a hydroxy, a carboxy, an epoxy, an isocyanate, a primary amine, a silyl, and an alkoxy silyl, and X is selected from the group consisting of Li⁺, Na⁺, K⁺, Cs⁺, and a quaternary ammonium; (h) a nido-carborane salt having the general formula R_(x)[CB_(n)H_(n+1−x)]X₃ wherein n is in the range of from 6 to 10, x is in the range of from 0 to 1, R is selected from the group consisting of a C₁ to C₂₀ n-alkyl, a hydroxy, a carboxy, an epoxy, an isocyanate, a primary amine, a silyl, and an alkoxy silyl, and X is selected from the group consisting of Li⁺, Na⁺, K⁺, Cs⁺, and a quaternary ammonium; and (i) mixtures of two or more thereof.
 14. The method of claim 1, wherein said matrix comprises a plurality of polymers.
 15. The method of claim 1, wherein said polymer is selected from the group consisting of an epoxy polymer, a polyurethane, poly(ethylene-co-vinyl acetate), poly(ethylene-co-vinyl acetate-co-vinyl alcohol), poly(ethylene-co-ethyl acrylate), poly(ethylene-co-octene), a polycyanurate, and mixtures of two or more thereof.
 16. The method of claim 1, wherein said hygroscopic salt is Li₂[B₁₂H₁₂].
 17. The method of claim 1, wherein said composition is part of an article of manufacture.
 18. A method of adjusting the properties of a material, said method comprising: providing a composition comprising: a matrix comprising a polymer, wherein said polymer comprises one or more residues of a cage compound monomer selected from the group consisting of a borane cage compound monomer, a carborane cage compound monomer, and mixtures thereof; and a filler comprising a hygroscopic salt; and exposing said composition to moisture under conditions for said composition to absorb said moisture.
 19. The method of claim 18, wherein said composition has a first glass transition temperature prior to said exposing, and a second glass transition after said exposing, said first glass transition temperature being at least about 1° C. greater than said second glass transition temperature within about 1 day after said exposing was begun.
 20. The method of claim 18, wherein said composition has a first glass transition temperature prior to said exposing, and a second glass transition after said exposing, said first glass transition temperature being at least about 10° C. greater than said second glass transition temperature within about 1 day after said exposing was begun.
 21. The method of claim 18, wherein said composition has a first glass transition temperature prior to said exposing, and a second glass transition after said exposing, said first glass transition temperature being from about 10° C. to about 100° C. greater than said second glass transition temperature within about 7 days after said exposing was begun.
 22. The method of claim 18, wherein said composition has a first glass transition temperature prior to said exposing, and a second glass transition after said exposing, said first glass transition temperature being from about 30° C. to about 100° C. greater than said second glass transition temperature within about 28 days after said exposing was begun.
 23. The method of claim 18, wherein said composition has a first storage modulus at room temperature prior to said exposing, and a second storage modulus at room temperature after said exposing, said second storage modulus being at least about 40% lower than said first storage modulus within about 1 day after said exposing was begun.
 24. The method of claim 18, wherein said composition has a first storage modulus at 0° C. prior to said exposing, and a second storage modulus at 0° C. after said exposing, said second storage modulus being at least about 30% lower than said first storage modulus within about 1 day after said exposing was begun.
 25. The method of claim 18, wherein said composition has a first storage modulus at −25° C. prior to said exposing, and a second storage modulus at −25° C. after said exposing, said second storage modulus being at least about 10% lower than said first storage modulus within about 1 day after said exposing was begun.
 26. The method of claim 18, said filler consisting essentially of said hygroscopic salt.
 27. The method of claim 26, said filler consisting of said hygroscopic salt.
 28. The method of claim 18, wherein said hygroscopic salt is Li₂[B₁₂H₁₂].
 29. The method of claim 18, wherein said filler comprises a cage compound selected from the group consisting of a borane cage compound, a carborane cage compound, a metal complex thereof, a residue thereof, mixtures thereof, and agglomerations thereof, wherein said cage compound comprises at least 7 cage atoms, wherein said cage compound is not covalently bound to said polymer
 30. The method of claim 18, wherein said matrix comprises an additional polymer, wherein said additional polymer is selected from the group consisting of an epoxy polymer, a polyurethane, a polysiloxane, poly(ethylene-co-vinyl acetate), poly(ethylene-co-vinyl acetate-co-vinyl alcohol), styrene-butadiene-styrene, poly(ethylene-co-ethyl acrylate), poly(ethylene-co-octene), a polycyanurate, and mixtures of two or more thereof, wherein said filler further comprises a material selected from the group consisting of carbon nanotubes, carbon fullerenes, polyhedral oligomeric silsesquioxane, boron nitride nanotubes, clay, and mixtures of two or more thereof.
 31. The method of claim 18, wherein said composition is part of an article of manufacture. 